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[PATCH 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. 283+ messages / 3 participants [nested] [flat]
* [PATCH v3 3/3] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. @ 2021-04-04 00:24 Justin Pryzby <pryzbyj@telsasoft.com> 0 siblings, 0 replies; 283+ messages in thread From: Justin Pryzby @ 2021-04-04 00:24 UTC (permalink / raw) ..to discourage users from changing this option in hopes that it'll make their queries faster, but without reading the documentation or understanding what it does. --- doc/src/sgml/config.sgml | 96 ++++++++++--------- src/backend/utils/misc/guc.c | 2 +- src/backend/utils/misc/postgresql.conf.sample | 1 - 3 files changed, 50 insertions(+), 49 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index f749fe9ce7..a7350c6ddc 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5912,51 +5912,6 @@ SELECT * FROM parent WHERE key = 2400; </listitem> </varlistentry> - <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> - <term><varname>force_parallel_mode</varname> (<type>enum</type>) - <indexterm> - <primary><varname>force_parallel_mode</varname> configuration parameter</primary> - </indexterm> - </term> - <listitem> - <para> - Allows the use of parallel queries for testing purposes even in cases - where no performance benefit is expected. - The allowed values of <varname>force_parallel_mode</varname> are - <literal>off</literal> (use parallel mode only when it is expected to improve - performance), <literal>on</literal> (force parallel query for all queries - for which it is thought to be safe), and <literal>regress</literal> (like - <literal>on</literal>, but with additional behavior changes as explained - below). - </para> - - <para> - More specifically, setting this value to <literal>on</literal> will add - a <literal>Gather</literal> node to the top of any query plan for which this - appears to be safe, so that the query runs inside of a parallel worker. - Even when a parallel worker is not available or cannot be used, - operations such as starting a subtransaction that would be prohibited - in a parallel query context will be prohibited unless the planner - believes that this will cause the query to fail. If failures or - unexpected results occur when this option is set, some functions used - by the query may need to be marked <literal>PARALLEL UNSAFE</literal> - (or, possibly, <literal>PARALLEL RESTRICTED</literal>). - </para> - - <para> - Setting this value to <literal>regress</literal> has all of the same effects - as setting it to <literal>on</literal> plus some additional effects that are - intended to facilitate automated regression testing. Normally, - messages from a parallel worker include a context line indicating that, - but a setting of <literal>regress</literal> suppresses this line so that the - output is the same as in non-parallel execution. Also, - the <literal>Gather</literal> nodes added to plans by this setting are hidden - in <literal>EXPLAIN</literal> output so that the output matches what - would be obtained if this setting were turned <literal>off</literal>. - </para> - </listitem> - </varlistentry> - <varlistentry id="guc-plan-cache_mode" xreflabel="plan_cache_mode"> <term><varname>plan_cache_mode</varname> (<type>enum</type>) <indexterm> @@ -10374,8 +10329,10 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' <title>Developer Options</title> <para> - The following parameters are intended for work on the - <productname>PostgreSQL</productname> source code, and in some cases + The following parameters are intended for development with + <productname>PostgreSQL</productname>. Some of them are useful while + writing SQL queries, some of them are useful when + working on the source code of PostgreSQL itself, and to assist with recovery of severely damaged databases. There should be no reason to use them on a production database. As such, they have been excluded from the sample @@ -10464,6 +10421,51 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' </listitem> </varlistentry> + <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> + <term><varname>force_parallel_mode</varname> (<type>enum</type>) + <indexterm> + <primary><varname>force_parallel_mode</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Allows the use of parallel queries for testing purposes even in cases + where no performance benefit is expected. + The allowed values of <varname>force_parallel_mode</varname> are + <literal>off</literal> (use parallel mode only when it is expected to improve + performance), <literal>on</literal> (force parallel query for all queries + for which it is thought to be safe), and <literal>regress</literal> (like + <literal>on</literal>, but with additional behavior changes as explained + below). + </para> + + <para> + More specifically, setting this value to <literal>on</literal> will add + a <literal>Gather</literal> node to the top of any query plan for which this + appears to be safe, so that the query runs inside of a parallel worker. + Even when a parallel worker is not available or cannot be used, + operations such as starting a subtransaction that would be prohibited + in a parallel query context will be prohibited unless the planner + believes that this will cause the query to fail. If failures or + unexpected results occur when this option is set, some functions used + by the query may need to be marked <literal>PARALLEL UNSAFE</literal> + (or, possibly, <literal>PARALLEL RESTRICTED</literal>). + </para> + + <para> + Setting this value to <literal>regress</literal> has all of the same effects + as setting it to <literal>on</literal> plus some additional effects that are + intended to facilitate automated regression testing. Normally, + messages from a parallel worker include a context line indicating that, + but a setting of <literal>regress</literal> suppresses this line so that the + output is the same as in non-parallel execution. Also, + the <literal>Gather</literal> nodes added to plans by this setting are hidden + in <literal>EXPLAIN</literal> output so that the output matches what + would be obtained if this setting were turned <literal>off</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-ignore-system-indexes" xreflabel="ignore_system_indexes"> <term><varname>ignore_system_indexes</varname> (<type>boolean</type>) <indexterm> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index a3c2ebbc53..b8738561e6 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -4922,7 +4922,7 @@ static struct config_enum ConfigureNamesEnum[] = }, { - {"force_parallel_mode", PGC_USERSET, QUERY_TUNING_OTHER, + {"force_parallel_mode", PGC_USERSET, DEVELOPER_OPTIONS, gettext_noop("Forces use of parallel query facilities."), gettext_noop("If possible, run query using a parallel worker and with parallel restrictions."), GUC_EXPLAIN diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 2f6dd014a8..0f7f49b949 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -421,7 +421,6 @@ #from_collapse_limit = 8 #join_collapse_limit = 8 # 1 disables collapsing of explicit # JOIN clauses -#force_parallel_mode = off #jit = on # allow JIT compilation #plan_cache_mode = auto # auto, force_generic_plan or # force_custom_plan -- 2.17.0 --oC1+HKm2/end4ao3-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v2 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. @ 2021-04-04 00:24 Justin Pryzby <pryzbyj@telsasoft.com> 0 siblings, 0 replies; 283+ messages in thread From: Justin Pryzby @ 2021-04-04 00:24 UTC (permalink / raw) ..to help avoid users finding this option and changing it in hopes that it'll make their queries faster, but without reading the documentation or understanding what it does. --- doc/src/sgml/config.sgml | 90 +++++++++---------- src/backend/utils/misc/guc.c | 2 +- src/backend/utils/misc/postgresql.conf.sample | 1 - 3 files changed, 46 insertions(+), 47 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index eb154cd669..4568a5c5a0 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5912,51 +5912,6 @@ SELECT * FROM parent WHERE key = 2400; </listitem> </varlistentry> - <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> - <term><varname>force_parallel_mode</varname> (<type>enum</type>) - <indexterm> - <primary><varname>force_parallel_mode</varname> configuration parameter</primary> - </indexterm> - </term> - <listitem> - <para> - Allows the use of parallel queries for testing purposes even in cases - where no performance benefit is expected. - The allowed values of <varname>force_parallel_mode</varname> are - <literal>off</literal> (use parallel mode only when it is expected to improve - performance), <literal>on</literal> (force parallel query for all queries - for which it is thought to be safe), and <literal>regress</literal> (like - <literal>on</literal>, but with additional behavior changes as explained - below). - </para> - - <para> - More specifically, setting this value to <literal>on</literal> will add - a <literal>Gather</literal> node to the top of any query plan for which this - appears to be safe, so that the query runs inside of a parallel worker. - Even when a parallel worker is not available or cannot be used, - operations such as starting a subtransaction that would be prohibited - in a parallel query context will be prohibited unless the planner - believes that this will cause the query to fail. If failures or - unexpected results occur when this option is set, some functions used - by the query may need to be marked <literal>PARALLEL UNSAFE</literal> - (or, possibly, <literal>PARALLEL RESTRICTED</literal>). - </para> - - <para> - Setting this value to <literal>regress</literal> has all of the same effects - as setting it to <literal>on</literal> plus some additional effects that are - intended to facilitate automated regression testing. Normally, - messages from a parallel worker include a context line indicating that, - but a setting of <literal>regress</literal> suppresses this line so that the - output is the same as in non-parallel execution. Also, - the <literal>Gather</literal> nodes added to plans by this setting are hidden - in <literal>EXPLAIN</literal> output so that the output matches what - would be obtained if this setting were turned <literal>off</literal>. - </para> - </listitem> - </varlistentry> - <varlistentry id="guc-plan-cache_mode" xreflabel="plan_cache_mode"> <term><varname>plan_cache_mode</varname> (<type>enum</type>) <indexterm> @@ -10462,6 +10417,51 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' </listitem> </varlistentry> + <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> + <term><varname>force_parallel_mode</varname> (<type>enum</type>) + <indexterm> + <primary><varname>force_parallel_mode</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Allows the use of parallel queries for testing purposes even in cases + where no performance benefit is expected. + The allowed values of <varname>force_parallel_mode</varname> are + <literal>off</literal> (use parallel mode only when it is expected to improve + performance), <literal>on</literal> (force parallel query for all queries + for which it is thought to be safe), and <literal>regress</literal> (like + <literal>on</literal>, but with additional behavior changes as explained + below). + </para> + + <para> + More specifically, setting this value to <literal>on</literal> will add + a <literal>Gather</literal> node to the top of any query plan for which this + appears to be safe, so that the query runs inside of a parallel worker. + Even when a parallel worker is not available or cannot be used, + operations such as starting a subtransaction that would be prohibited + in a parallel query context will be prohibited unless the planner + believes that this will cause the query to fail. If failures or + unexpected results occur when this option is set, some functions used + by the query may need to be marked <literal>PARALLEL UNSAFE</literal> + (or, possibly, <literal>PARALLEL RESTRICTED</literal>). + </para> + + <para> + Setting this value to <literal>regress</literal> has all of the same effects + as setting it to <literal>on</literal> plus some additional effects that are + intended to facilitate automated regression testing. Normally, + messages from a parallel worker include a context line indicating that, + but a setting of <literal>regress</literal> suppresses this line so that the + output is the same as in non-parallel execution. Also, + the <literal>Gather</literal> nodes added to plans by this setting are hidden + in <literal>EXPLAIN</literal> output so that the output matches what + would be obtained if this setting were turned <literal>off</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-ignore-system-indexes" xreflabel="ignore_system_indexes"> <term><varname>ignore_system_indexes</varname> (<type>boolean</type>) <indexterm> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 2b9583cc77..598813da2d 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -4922,7 +4922,7 @@ static struct config_enum ConfigureNamesEnum[] = }, { - {"force_parallel_mode", PGC_USERSET, QUERY_TUNING_OTHER, + {"force_parallel_mode", PGC_USERSET, DEVELOPER_OPTIONS, gettext_noop("Forces use of parallel query facilities."), gettext_noop("If possible, run query using a parallel worker and with parallel restrictions."), GUC_EXPLAIN diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index cc9edc410f..a38fe18886 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -421,7 +421,6 @@ #from_collapse_limit = 8 #join_collapse_limit = 8 # 1 disables collapsing of explicit # JOIN clauses -#force_parallel_mode = off #jit = on # allow JIT compilation #plan_cache_mode = auto # auto, force_generic_plan or # force_custom_plan -- 2.17.0 --0eh6TmSyL6TZE2Uz-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. @ 2021-04-04 00:24 Justin Pryzby <pryzbyj@telsasoft.com> 0 siblings, 0 replies; 283+ messages in thread From: Justin Pryzby @ 2021-04-04 00:24 UTC (permalink / raw) ..to help avoid users finding this option and changing it in hopes that it'll make their queries faster, but without reading the documentation or understanding what it does. --- doc/src/sgml/config.sgml | 90 +++++++++---------- src/backend/utils/misc/guc.c | 2 +- src/backend/utils/misc/postgresql.conf.sample | 1 - 3 files changed, 46 insertions(+), 47 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index c4d5126c2a..5c7c5a39ca 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5788,51 +5788,6 @@ SELECT * FROM parent WHERE key = 2400; </listitem> </varlistentry> - <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> - <term><varname>force_parallel_mode</varname> (<type>enum</type>) - <indexterm> - <primary><varname>force_parallel_mode</varname> configuration parameter</primary> - </indexterm> - </term> - <listitem> - <para> - Allows the use of parallel queries for testing purposes even in cases - where no performance benefit is expected. - The allowed values of <varname>force_parallel_mode</varname> are - <literal>off</literal> (use parallel mode only when it is expected to improve - performance), <literal>on</literal> (force parallel query for all queries - for which it is thought to be safe), and <literal>regress</literal> (like - <literal>on</literal>, but with additional behavior changes as explained - below). - </para> - - <para> - More specifically, setting this value to <literal>on</literal> will add - a <literal>Gather</literal> node to the top of any query plan for which this - appears to be safe, so that the query runs inside of a parallel worker. - Even when a parallel worker is not available or cannot be used, - operations such as starting a subtransaction that would be prohibited - in a parallel query context will be prohibited unless the planner - believes that this will cause the query to fail. If failures or - unexpected results occur when this option is set, some functions used - by the query may need to be marked <literal>PARALLEL UNSAFE</literal> - (or, possibly, <literal>PARALLEL RESTRICTED</literal>). - </para> - - <para> - Setting this value to <literal>regress</literal> has all of the same effects - as setting it to <literal>on</literal> plus some additional effects that are - intended to facilitate automated regression testing. Normally, - messages from a parallel worker include a context line indicating that, - but a setting of <literal>regress</literal> suppresses this line so that the - output is the same as in non-parallel execution. Also, - the <literal>Gather</literal> nodes added to plans by this setting are hidden - in <literal>EXPLAIN</literal> output so that the output matches what - would be obtained if this setting were turned <literal>off</literal>. - </para> - </listitem> - </varlistentry> - <varlistentry id="guc-plan-cache_mode" xreflabel="plan_cache_mode"> <term><varname>plan_cache_mode</varname> (<type>enum</type>) <indexterm> @@ -10231,6 +10186,51 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' </listitem> </varlistentry> + <varlistentry id="guc-force-parallel-mode" xreflabel="force_parallel_mode"> + <term><varname>force_parallel_mode</varname> (<type>enum</type>) + <indexterm> + <primary><varname>force_parallel_mode</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Allows the use of parallel queries for testing purposes even in cases + where no performance benefit is expected. + The allowed values of <varname>force_parallel_mode</varname> are + <literal>off</literal> (use parallel mode only when it is expected to improve + performance), <literal>on</literal> (force parallel query for all queries + for which it is thought to be safe), and <literal>regress</literal> (like + <literal>on</literal>, but with additional behavior changes as explained + below). + </para> + + <para> + More specifically, setting this value to <literal>on</literal> will add + a <literal>Gather</literal> node to the top of any query plan for which this + appears to be safe, so that the query runs inside of a parallel worker. + Even when a parallel worker is not available or cannot be used, + operations such as starting a subtransaction that would be prohibited + in a parallel query context will be prohibited unless the planner + believes that this will cause the query to fail. If failures or + unexpected results occur when this option is set, some functions used + by the query may need to be marked <literal>PARALLEL UNSAFE</literal> + (or, possibly, <literal>PARALLEL RESTRICTED</literal>). + </para> + + <para> + Setting this value to <literal>regress</literal> has all of the same effects + as setting it to <literal>on</literal> plus some additional effects that are + intended to facilitate automated regression testing. Normally, + messages from a parallel worker include a context line indicating that, + but a setting of <literal>regress</literal> suppresses this line so that the + output is the same as in non-parallel execution. Also, + the <literal>Gather</literal> nodes added to plans by this setting are hidden + in <literal>EXPLAIN</literal> output so that the output matches what + would be obtained if this setting were turned <literal>off</literal>. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-ignore-system-indexes" xreflabel="ignore_system_indexes"> <term><varname>ignore_system_indexes</varname> (<type>boolean</type>) <indexterm> diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 27287599ad..06de7c0308 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -4840,7 +4840,7 @@ static struct config_enum ConfigureNamesEnum[] = }, { - {"force_parallel_mode", PGC_USERSET, QUERY_TUNING_OTHER, + {"force_parallel_mode", PGC_USERSET, DEVELOPER_OPTIONS, gettext_noop("Forces use of parallel query facilities."), gettext_noop("If possible, run query using a parallel worker and with parallel restrictions."), GUC_EXPLAIN diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 52c4373a79..50faa50462 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -415,7 +415,6 @@ #from_collapse_limit = 8 #join_collapse_limit = 8 # 1 disables collapsing of explicit # JOIN clauses -#force_parallel_mode = off #jit = on # allow JIT compilation #plan_cache_mode = auto # auto, force_generic_plan or # force_custom_plan -- 2.17.0 --GyRA7555PLgSTuth-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v17] Avoid orphaned objects dependencies @ 2024-03-29 15:43 Bertrand Drouvot <bertranddrouvot.pg@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: Bertrand Drouvot @ 2024-03-29 15:43 UTC (permalink / raw) It's currently possible to create orphaned objects dependencies, for example: Scenario 1: session 1: begin; drop schema schem; session 2: create a function in the schema schem session 1: commit; With the above, the function created in session 2 would be linked to a non existing schema. Scenario 2: session 1: begin; create a function in the schema schem session 2: drop schema schem; session 1: commit; With the above, the function created in session 1 would be linked to a non existing schema. To avoid those scenarios, a new lock (that conflicts with a lock taken by DROP) has been put in place before the dependencies are being recorded. With this in place, the drop schema in scenario 2 would be locked. Also, after the new lock attempt, the patch checks that the object still exists: with this in place session 2 in scenario 1 would be locked and would report an error once session 1 committs (that would not be the case should session 1 abort the transaction). If the object is dropped before the new lock attempt is triggered then the patch would also report an error (but with less details). The patch takes into account any type of objects except the ones that are pinned (they are not droppable because the system requires it). A special case is done for objects that belong to the RelationRelationId class. For those, we should be in one of the two following cases that would already prevent the relation to be dropped: 1. The relation is already locked (could be an existing relation or a relation that we are creating). 2. The relation is protected indirectly (i.e an index protected by a lock on its table, a table protected by a lock on a function that depends the table...) To avoid any risks for the RelationRelationId class case, we acquire a lock if there is none. That may add unnecessary lock for 2. but that's worth it. The patch adds a few tests for some dependency cases (that would currently produce orphaned objects): - schema and function (as the above scenarios) - alter a dependency (function and schema) - function and arg type - function and return type - function and function - domain and domain - table and type - server and foreign data wrapper --- src/backend/catalog/aclchk.c | 1 + src/backend/catalog/dependency.c | 212 ++++++++++++++++++ src/backend/catalog/heap.c | 7 + src/backend/catalog/index.c | 26 +++ src/backend/catalog/objectaddress.c | 57 +++++ src/backend/catalog/pg_aggregate.c | 9 + src/backend/catalog/pg_attrdef.c | 1 + src/backend/catalog/pg_cast.c | 5 + src/backend/catalog/pg_collation.c | 1 + src/backend/catalog/pg_constraint.c | 26 +++ src/backend/catalog/pg_conversion.c | 2 + src/backend/catalog/pg_depend.c | 39 +++- src/backend/catalog/pg_operator.c | 19 ++ src/backend/catalog/pg_proc.c | 17 +- src/backend/catalog/pg_publication.c | 11 + src/backend/catalog/pg_range.c | 6 + src/backend/catalog/pg_type.c | 39 ++++ src/backend/catalog/toasting.c | 1 + src/backend/commands/alter.c | 4 + src/backend/commands/amcmds.c | 1 + src/backend/commands/cluster.c | 7 + src/backend/commands/event_trigger.c | 1 + src/backend/commands/extension.c | 5 + src/backend/commands/foreigncmds.c | 7 + src/backend/commands/functioncmds.c | 6 + src/backend/commands/indexcmds.c | 2 + src/backend/commands/opclasscmds.c | 18 ++ src/backend/commands/operatorcmds.c | 30 +++ src/backend/commands/policy.c | 2 + src/backend/commands/proclang.c | 3 + src/backend/commands/sequence.c | 2 + src/backend/commands/statscmds.c | 10 + src/backend/commands/tablecmds.c | 24 +- src/backend/commands/trigger.c | 29 ++- src/backend/commands/tsearchcmds.c | 73 +++++- src/backend/commands/typecmds.c | 84 +++++++ src/backend/rewrite/rewriteDefine.c | 1 + src/backend/utils/errcodes.txt | 1 + src/include/catalog/dependency.h | 3 + src/include/catalog/objectaddress.h | 1 + .../expected/test_dependencies_locks.out | 129 +++++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/test_dependencies_locks.spec | 89 ++++++++ .../test_oat_hooks/expected/alter_table.out | 4 +- .../expected/test_oat_hooks.out | 2 + src/test/regress/expected/alter_table.out | 11 +- 46 files changed, 1009 insertions(+), 20 deletions(-) 40.0% src/backend/catalog/ 29.8% src/backend/commands/ 16.8% src/test/isolation/expected/ 10.5% src/test/isolation/specs/ diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c index 95eb0b1227..176bd46261 100644 --- a/src/backend/catalog/aclchk.c +++ b/src/backend/catalog/aclchk.c @@ -1414,6 +1414,7 @@ SetDefaultACL(InternalDefaultACL *iacls) referenced.objectId = iacls->nspid; referenced.objectSubId = 0; + LockNotPinnedObject(NamespaceRelationId, iacls->nspid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); } } diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c index 0489cbabcb..a3770d7206 100644 --- a/src/backend/catalog/dependency.c +++ b/src/backend/catalog/dependency.c @@ -1519,6 +1519,81 @@ AcquireDeletionLock(const ObjectAddress *object, int flags) } } +/* + * LockNotPinnedObjectById + * + * Lock the object that we are about to record a dependency on. + * After it's locked, verify that it hasn't been dropped while we + * weren't looking. If the object has been dropped, this function + * does not return! + */ +void +LockNotPinnedObjectById(const ObjectAddress *object) +{ + char *object_description = NULL; + + if (isObjectPinned(object)) + return; + + object_description = getObjectDescription(object, true); + + if (object->classId == RelationRelationId) + { + Assert(!IsSharedRelation(object->objectId)); + + /* + * We must be in one of the two following cases that would already + * prevent the relation to be dropped: 1. The relation is already + * locked (could be an existing relation or a relation that we are + * creating). 2. The relation is protected indirectly (i.e an index + * protected by a lock on its table, a table protected by a lock on a + * function that depends of the table...). To avoid any risks, acquire + * a lock if there is none. That may add unnecessary lock for 2. but + * that's worth it. + */ + if (!CheckRelationOidLockedByMe(object->objectId, AccessShareLock, true)) + LockRelationOid(object->objectId, AccessShareLock); + } + else + { + /* assume we should lock the whole object not a sub-object */ + LockDatabaseObject(object->classId, object->objectId, 0, AccessShareLock); + } + + /* check if object still exists */ + if (!ObjectByIdExist(object)) + { + if (object_description) + ereport(ERROR, + (errcode(ERRCODE_DEPENDENT_OBJECTS_DOES_NOT_EXIST), + errmsg("%s does not exist", object_description))); + else + ereport(ERROR, + (errcode(ERRCODE_DEPENDENT_OBJECTS_DOES_NOT_EXIST), + errmsg("a dependent object does not exist"))); + } + + if (object_description) + pfree(object_description); + + return; +} + +/* + * LockNotPinnedObject + * + * Lock the object that we are about to record a dependency on. + */ +void +LockNotPinnedObject(Oid classid, Oid objid) +{ + ObjectAddress object; + + ObjectAddressSet(object, classid, objid); + + LockNotPinnedObjectById(&object); +} + /* * ReleaseDeletionLock - release an object deletion lock * @@ -1730,6 +1805,7 @@ find_expr_references_walker(Node *node, if (rte->rtekind == RTE_RELATION) { /* If it's a plain relation, reference this column */ + LockNotPinnedObject(RelationRelationId, rte->relid); add_object_address(RelationRelationId, rte->relid, var->varattno, context->addrs); } @@ -1756,6 +1832,7 @@ find_expr_references_walker(Node *node, Oid objoid; /* A constant must depend on the constant's datatype */ + LockNotPinnedObject(TypeRelationId, con->consttype); add_object_address(TypeRelationId, con->consttype, 0, context->addrs); @@ -1767,8 +1844,11 @@ find_expr_references_walker(Node *node, */ if (OidIsValid(con->constcollid) && con->constcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, con->constcollid); add_object_address(CollationRelationId, con->constcollid, 0, context->addrs); + } /* * If it's a regclass or similar literal referring to an existing @@ -1785,59 +1865,83 @@ find_expr_references_walker(Node *node, objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(PROCOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(ProcedureRelationId, objoid); add_object_address(ProcedureRelationId, objoid, 0, context->addrs); + } break; case REGOPEROID: case REGOPERATOROID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(OPEROID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(OperatorRelationId, objoid); add_object_address(OperatorRelationId, objoid, 0, context->addrs); + } break; case REGCLASSOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(RELOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(RelationRelationId, objoid); add_object_address(RelationRelationId, objoid, 0, context->addrs); + } break; case REGTYPEOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(TYPEOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(TypeRelationId, objoid); add_object_address(TypeRelationId, objoid, 0, context->addrs); + } break; case REGCOLLATIONOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(COLLOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(CollationRelationId, objoid); add_object_address(CollationRelationId, objoid, 0, context->addrs); + } break; case REGCONFIGOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(TSCONFIGOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(TSConfigRelationId, objoid); add_object_address(TSConfigRelationId, objoid, 0, context->addrs); + } break; case REGDICTIONARYOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(TSDICTOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(TSDictionaryRelationId, objoid); add_object_address(TSDictionaryRelationId, objoid, 0, context->addrs); + } break; case REGNAMESPACEOID: objoid = DatumGetObjectId(con->constvalue); if (SearchSysCacheExists1(NAMESPACEOID, ObjectIdGetDatum(objoid))) + { + LockNotPinnedObject(NamespaceRelationId, objoid); add_object_address(NamespaceRelationId, objoid, 0, context->addrs); + } break; /* @@ -1859,18 +1963,23 @@ find_expr_references_walker(Node *node, Param *param = (Param *) node; /* A parameter must depend on the parameter's datatype */ + LockNotPinnedObject(TypeRelationId, param->paramtype); add_object_address(TypeRelationId, param->paramtype, 0, context->addrs); /* and its collation, just as for Consts */ if (OidIsValid(param->paramcollid) && param->paramcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, param->paramcollid); add_object_address(CollationRelationId, param->paramcollid, 0, context->addrs); + } } else if (IsA(node, FuncExpr)) { FuncExpr *funcexpr = (FuncExpr *) node; + LockNotPinnedObject(ProcedureRelationId, funcexpr->funcid); add_object_address(ProcedureRelationId, funcexpr->funcid, 0, context->addrs); /* fall through to examine arguments */ @@ -1879,6 +1988,7 @@ find_expr_references_walker(Node *node, { OpExpr *opexpr = (OpExpr *) node; + LockNotPinnedObject(OperatorRelationId, opexpr->opno); add_object_address(OperatorRelationId, opexpr->opno, 0, context->addrs); /* fall through to examine arguments */ @@ -1887,6 +1997,7 @@ find_expr_references_walker(Node *node, { DistinctExpr *distinctexpr = (DistinctExpr *) node; + LockNotPinnedObject(OperatorRelationId, distinctexpr->opno); add_object_address(OperatorRelationId, distinctexpr->opno, 0, context->addrs); /* fall through to examine arguments */ @@ -1895,6 +2006,7 @@ find_expr_references_walker(Node *node, { NullIfExpr *nullifexpr = (NullIfExpr *) node; + LockNotPinnedObject(OperatorRelationId, nullifexpr->opno); add_object_address(OperatorRelationId, nullifexpr->opno, 0, context->addrs); /* fall through to examine arguments */ @@ -1903,6 +2015,7 @@ find_expr_references_walker(Node *node, { ScalarArrayOpExpr *opexpr = (ScalarArrayOpExpr *) node; + LockNotPinnedObject(OperatorRelationId, opexpr->opno); add_object_address(OperatorRelationId, opexpr->opno, 0, context->addrs); /* fall through to examine arguments */ @@ -1911,6 +2024,7 @@ find_expr_references_walker(Node *node, { Aggref *aggref = (Aggref *) node; + LockNotPinnedObject(ProcedureRelationId, aggref->aggfnoid); add_object_address(ProcedureRelationId, aggref->aggfnoid, 0, context->addrs); /* fall through to examine arguments */ @@ -1919,6 +2033,7 @@ find_expr_references_walker(Node *node, { WindowFunc *wfunc = (WindowFunc *) node; + LockNotPinnedObject(ProcedureRelationId, wfunc->winfnoid); add_object_address(ProcedureRelationId, wfunc->winfnoid, 0, context->addrs); /* fall through to examine arguments */ @@ -1935,8 +2050,11 @@ find_expr_references_walker(Node *node, */ if (sbsref->refrestype != sbsref->refcontainertype && sbsref->refrestype != sbsref->refelemtype) + { + LockNotPinnedObject(TypeRelationId, sbsref->refrestype); add_object_address(TypeRelationId, sbsref->refrestype, 0, context->addrs); + } /* fall through to examine arguments */ } else if (IsA(node, SubPlan)) @@ -1960,16 +2078,25 @@ find_expr_references_walker(Node *node, * anywhere else in the expression. */ if (OidIsValid(reltype)) + { + LockNotPinnedObject(RelationRelationId, reltype); add_object_address(RelationRelationId, reltype, fselect->fieldnum, context->addrs); + } else + { + LockNotPinnedObject(TypeRelationId, fselect->resulttype); add_object_address(TypeRelationId, fselect->resulttype, 0, context->addrs); + } /* the collation might not be referenced anywhere else, either */ if (OidIsValid(fselect->resultcollid) && fselect->resultcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, fselect->resultcollid); add_object_address(CollationRelationId, fselect->resultcollid, 0, context->addrs); + } } else if (IsA(node, FieldStore)) { @@ -1980,53 +2107,76 @@ find_expr_references_walker(Node *node, if (OidIsValid(reltype)) { ListCell *l; + bool locked = false; foreach(l, fstore->fieldnums) + { + if (!locked) + { + LockNotPinnedObject(RelationRelationId, reltype); + locked = true; + } add_object_address(RelationRelationId, reltype, lfirst_int(l), context->addrs); + } } else + { + LockNotPinnedObject(TypeRelationId, fstore->resulttype); add_object_address(TypeRelationId, fstore->resulttype, 0, context->addrs); + } } else if (IsA(node, RelabelType)) { RelabelType *relab = (RelabelType *) node; /* since there is no function dependency, need to depend on type */ + LockNotPinnedObject(TypeRelationId, relab->resulttype); add_object_address(TypeRelationId, relab->resulttype, 0, context->addrs); /* the collation might not be referenced anywhere else, either */ if (OidIsValid(relab->resultcollid) && relab->resultcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, relab->resultcollid); add_object_address(CollationRelationId, relab->resultcollid, 0, context->addrs); + } } else if (IsA(node, CoerceViaIO)) { CoerceViaIO *iocoerce = (CoerceViaIO *) node; /* since there is no exposed function, need to depend on type */ + LockNotPinnedObject(TypeRelationId, iocoerce->resulttype); add_object_address(TypeRelationId, iocoerce->resulttype, 0, context->addrs); /* the collation might not be referenced anywhere else, either */ if (OidIsValid(iocoerce->resultcollid) && iocoerce->resultcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, iocoerce->resultcollid); add_object_address(CollationRelationId, iocoerce->resultcollid, 0, context->addrs); + } } else if (IsA(node, ArrayCoerceExpr)) { ArrayCoerceExpr *acoerce = (ArrayCoerceExpr *) node; /* as above, depend on type */ + LockNotPinnedObject(TypeRelationId, acoerce->resulttype); add_object_address(TypeRelationId, acoerce->resulttype, 0, context->addrs); /* the collation might not be referenced anywhere else, either */ if (OidIsValid(acoerce->resultcollid) && acoerce->resultcollid != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, acoerce->resultcollid); add_object_address(CollationRelationId, acoerce->resultcollid, 0, context->addrs); + } /* fall through to examine arguments */ } else if (IsA(node, ConvertRowtypeExpr)) @@ -2034,6 +2184,7 @@ find_expr_references_walker(Node *node, ConvertRowtypeExpr *cvt = (ConvertRowtypeExpr *) node; /* since there is no function dependency, need to depend on type */ + LockNotPinnedObject(TypeRelationId, cvt->resulttype); add_object_address(TypeRelationId, cvt->resulttype, 0, context->addrs); } @@ -2041,6 +2192,7 @@ find_expr_references_walker(Node *node, { CollateExpr *coll = (CollateExpr *) node; + LockNotPinnedObject(CollationRelationId, coll->collOid); add_object_address(CollationRelationId, coll->collOid, 0, context->addrs); } @@ -2048,6 +2200,7 @@ find_expr_references_walker(Node *node, { RowExpr *rowexpr = (RowExpr *) node; + LockNotPinnedObject(TypeRelationId, rowexpr->row_typeid); add_object_address(TypeRelationId, rowexpr->row_typeid, 0, context->addrs); } @@ -2058,11 +2211,13 @@ find_expr_references_walker(Node *node, foreach(l, rcexpr->opnos) { + LockNotPinnedObject(OperatorRelationId, lfirst_oid(l)); add_object_address(OperatorRelationId, lfirst_oid(l), 0, context->addrs); } foreach(l, rcexpr->opfamilies) { + LockNotPinnedObject(OperatorFamilyRelationId, lfirst_oid(l)); add_object_address(OperatorFamilyRelationId, lfirst_oid(l), 0, context->addrs); } @@ -2072,6 +2227,7 @@ find_expr_references_walker(Node *node, { CoerceToDomain *cd = (CoerceToDomain *) node; + LockNotPinnedObject(TypeRelationId, cd->resulttype); add_object_address(TypeRelationId, cd->resulttype, 0, context->addrs); } @@ -2079,6 +2235,7 @@ find_expr_references_walker(Node *node, { NextValueExpr *nve = (NextValueExpr *) node; + LockNotPinnedObject(RelationRelationId, nve->seqid); add_object_address(RelationRelationId, nve->seqid, 0, context->addrs); } @@ -2087,19 +2244,26 @@ find_expr_references_walker(Node *node, OnConflictExpr *onconflict = (OnConflictExpr *) node; if (OidIsValid(onconflict->constraint)) + { + LockNotPinnedObject(ConstraintRelationId, onconflict->constraint); add_object_address(ConstraintRelationId, onconflict->constraint, 0, context->addrs); + } /* fall through to examine arguments */ } else if (IsA(node, SortGroupClause)) { SortGroupClause *sgc = (SortGroupClause *) node; + LockNotPinnedObject(OperatorRelationId, sgc->eqop); add_object_address(OperatorRelationId, sgc->eqop, 0, context->addrs); if (OidIsValid(sgc->sortop)) + { + LockNotPinnedObject(OperatorRelationId, sgc->sortop); add_object_address(OperatorRelationId, sgc->sortop, 0, context->addrs); + } return false; } else if (IsA(node, WindowClause)) @@ -2107,15 +2271,24 @@ find_expr_references_walker(Node *node, WindowClause *wc = (WindowClause *) node; if (OidIsValid(wc->startInRangeFunc)) + { + LockNotPinnedObject(ProcedureRelationId, wc->startInRangeFunc); add_object_address(ProcedureRelationId, wc->startInRangeFunc, 0, context->addrs); + } if (OidIsValid(wc->endInRangeFunc)) + { + LockNotPinnedObject(ProcedureRelationId, wc->endInRangeFunc); add_object_address(ProcedureRelationId, wc->endInRangeFunc, 0, context->addrs); + } if (OidIsValid(wc->inRangeColl) && wc->inRangeColl != DEFAULT_COLLATION_OID) + { + LockNotPinnedObject(CollationRelationId, wc->inRangeColl); add_object_address(CollationRelationId, wc->inRangeColl, 0, context->addrs); + } /* fall through to examine substructure */ } else if (IsA(node, CTECycleClause)) @@ -2123,14 +2296,23 @@ find_expr_references_walker(Node *node, CTECycleClause *cc = (CTECycleClause *) node; if (OidIsValid(cc->cycle_mark_type)) + { + LockNotPinnedObject(TypeRelationId, cc->cycle_mark_type); add_object_address(TypeRelationId, cc->cycle_mark_type, 0, context->addrs); + } if (OidIsValid(cc->cycle_mark_collation)) + { + LockNotPinnedObject(CollationRelationId, cc->cycle_mark_collation); add_object_address(CollationRelationId, cc->cycle_mark_collation, 0, context->addrs); + } if (OidIsValid(cc->cycle_mark_neop)) + { + LockNotPinnedObject(OperatorRelationId, cc->cycle_mark_neop); add_object_address(OperatorRelationId, cc->cycle_mark_neop, 0, context->addrs); + } /* fall through to examine substructure */ } else if (IsA(node, Query)) @@ -2163,6 +2345,7 @@ find_expr_references_walker(Node *node, switch (rte->rtekind) { case RTE_RELATION: + LockNotPinnedObject(RelationRelationId, rte->relid); add_object_address(RelationRelationId, rte->relid, 0, context->addrs); break; @@ -2215,12 +2398,18 @@ find_expr_references_walker(Node *node, rte = rt_fetch(query->resultRelation, query->rtable); if (rte->rtekind == RTE_RELATION) { + bool locked = false; foreach(lc, query->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(lc); if (tle->resjunk) continue; /* ignore junk tlist items */ + if (!locked) + { + LockNotPinnedObject(RelationRelationId, rte->relid); + locked = true; + } add_object_address(RelationRelationId, rte->relid, tle->resno, context->addrs); } @@ -2232,6 +2421,7 @@ find_expr_references_walker(Node *node, */ foreach(lc, query->constraintDeps) { + LockNotPinnedObject(ConstraintRelationId, lfirst_oid(lc)); add_object_address(ConstraintRelationId, lfirst_oid(lc), 0, context->addrs); } @@ -2266,16 +2456,25 @@ find_expr_references_walker(Node *node, */ foreach(ct, rtfunc->funccoltypes) { + LockNotPinnedObject(TypeRelationId, lfirst_oid(ct)); add_object_address(TypeRelationId, lfirst_oid(ct), 0, context->addrs); } foreach(ct, rtfunc->funccolcollations) { Oid collid = lfirst_oid(ct); + bool locked = false; if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID) + { + if (!locked) + { + LockNotPinnedObject(CollationRelationId, collid); + locked = true; + } add_object_address(CollationRelationId, collid, 0, context->addrs); + } } } else if (IsA(node, TableFunc)) @@ -2288,22 +2487,32 @@ find_expr_references_walker(Node *node, */ foreach(ct, tf->coltypes) { + LockNotPinnedObject(TypeRelationId, lfirst_oid(ct)); add_object_address(TypeRelationId, lfirst_oid(ct), 0, context->addrs); } foreach(ct, tf->colcollations) { Oid collid = lfirst_oid(ct); + bool locked = false; if (OidIsValid(collid) && collid != DEFAULT_COLLATION_OID) + { + if (!locked) + { + LockNotPinnedObject(CollationRelationId, collid); + locked = true; + } add_object_address(CollationRelationId, collid, 0, context->addrs); + } } } else if (IsA(node, TableSampleClause)) { TableSampleClause *tsc = (TableSampleClause *) node; + LockNotPinnedObject(ProcedureRelationId, tsc->tsmhandler); add_object_address(ProcedureRelationId, tsc->tsmhandler, 0, context->addrs); /* fall through to examine arguments */ @@ -2354,9 +2563,12 @@ process_function_rte_ref(RangeTblEntry *rte, AttrNumber attnum, Assert(attnum - atts_done <= tupdesc->natts); if (OidIsValid(reltype)) /* can this fail? */ + { + LockNotPinnedObject(RelationRelationId, reltype); add_object_address(RelationRelationId, reltype, attnum - atts_done, context->addrs); + } return; } /* Nothing to do; function's result type is handled elsewhere */ diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c index 0078a12f26..e92c8363e0 100644 --- a/src/backend/catalog/heap.c +++ b/src/backend/catalog/heap.c @@ -844,6 +844,7 @@ AddNewAttributeTuples(Oid new_rel_oid, /* Add dependency info */ ObjectAddressSubSet(myself, RelationRelationId, new_rel_oid, i + 1); ObjectAddressSet(referenced, TypeRelationId, attr->atttypid); + LockNotPinnedObject(TypeRelationId, attr->atttypid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* The default collation is pinned, so don't bother recording it */ @@ -852,6 +853,7 @@ AddNewAttributeTuples(Oid new_rel_oid, { ObjectAddressSet(referenced, CollationRelationId, attr->attcollation); + LockNotPinnedObject(CollationRelationId, attr->attcollation); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } } @@ -1459,11 +1461,13 @@ heap_create_with_catalog(const char *relname, ObjectAddressSet(referenced, NamespaceRelationId, relnamespace); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(NamespaceRelationId, relnamespace); if (reloftypeid) { ObjectAddressSet(referenced, TypeRelationId, reloftypeid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, reloftypeid); } /* @@ -1477,6 +1481,7 @@ heap_create_with_catalog(const char *relname, { ObjectAddressSet(referenced, AccessMethodRelationId, accessmtd); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(AccessMethodRelationId, accessmtd); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); @@ -3390,6 +3395,7 @@ StorePartitionKey(Relation rel, { ObjectAddressSet(referenced, OperatorClassRelationId, partopclass[i]); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(OperatorClassRelationId, partopclass[i]); /* The default collation is pinned, so don't bother recording it */ if (OidIsValid(partcollation[i]) && @@ -3397,6 +3403,7 @@ StorePartitionKey(Relation rel, { ObjectAddressSet(referenced, CollationRelationId, partcollation[i]); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(CollationRelationId, partcollation[i]); } } diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 9162b9f81a..0ede0fd153 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -1116,6 +1116,7 @@ index_create(Relation heapRelation, else { bool have_simple_col = false; + bool locked_object = false; addrs = new_object_addresses(); @@ -1128,6 +1129,12 @@ index_create(Relation heapRelation, heapRelationId, indexInfo->ii_IndexAttrNumbers[i]); add_exact_object_address(&referenced, addrs); + + if (!locked_object) + { + LockNotPinnedObject(RelationRelationId, heapRelationId); + locked_object = true; + } have_simple_col = true; } } @@ -1143,6 +1150,8 @@ index_create(Relation heapRelation, ObjectAddressSet(referenced, RelationRelationId, heapRelationId); add_exact_object_address(&referenced, addrs); + + LockNotPinnedObject(RelationRelationId, heapRelationId); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_AUTO); @@ -1158,9 +1167,13 @@ index_create(Relation heapRelation, if (OidIsValid(parentIndexRelid)) { ObjectAddressSet(referenced, RelationRelationId, parentIndexRelid); + + LockNotPinnedObject(RelationRelationId, parentIndexRelid); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, heapRelationId); + + LockNotPinnedObject(RelationRelationId, heapRelationId); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC); } @@ -1176,6 +1189,7 @@ index_create(Relation heapRelation, { ObjectAddressSet(referenced, CollationRelationId, collationIds[i]); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(CollationRelationId, collationIds[i]); } } @@ -1184,6 +1198,7 @@ index_create(Relation heapRelation, { ObjectAddressSet(referenced, OperatorClassRelationId, opclassIds[i]); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(OperatorClassRelationId, opclassIds[i]); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); @@ -1993,6 +2008,14 @@ index_constraint_create(Relation heapRelation, */ ObjectAddressSet(myself, ConstraintRelationId, conOid); ObjectAddressSet(idxaddr, RelationRelationId, indexRelationId); + + /* + * CommandCounterIncrement() here to ensure the new constraint entry is + * visible when LockNotPinnedObject() will check its existence before + * recording the dependencies. + */ + CommandCounterIncrement(); + LockNotPinnedObject(ConstraintRelationId, conOid); recordDependencyOn(&idxaddr, &myself, DEPENDENCY_INTERNAL); /* @@ -2004,9 +2027,12 @@ index_constraint_create(Relation heapRelation, ObjectAddress referenced; ObjectAddressSet(referenced, ConstraintRelationId, parentConstraintId); + LockNotPinnedObject(ConstraintRelationId, parentConstraintId); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(heapRelation)); + + LockNotPinnedObject(RelationRelationId, RelationGetRelid(heapRelation)); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC); } diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c index 85a7b7e641..17c4085948 100644 --- a/src/backend/catalog/objectaddress.c +++ b/src/backend/catalog/objectaddress.c @@ -2590,6 +2590,63 @@ get_object_namespace(const ObjectAddress *address) return oid; } +/* + * ObjectByIdExist + * + * Return whether the given object exists. + * + * Works for most catalogs, if no special processing is needed. + */ +bool +ObjectByIdExist(const ObjectAddress *address) +{ + HeapTuple tuple; + int cache; + const ObjectPropertyType *property; + + property = get_object_property_data(address->classId); + + cache = property->oid_catcache_id; + + if (cache >= 0) + { + /* Fetch tuple from syscache. */ + tuple = SearchSysCache1(cache, ObjectIdGetDatum(address->objectId)); + + if (!HeapTupleIsValid(tuple)) + { + return false; + } + + ReleaseSysCache(tuple); + + return true; + } + else + { + Relation rel; + ScanKeyData skey[1]; + SysScanDesc scan; + + rel = table_open(address->classId, AccessShareLock); + + ScanKeyInit(&skey[0], + get_object_attnum_oid(address->classId), + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(address->objectId)); + + scan = systable_beginscan(rel, get_object_oid_index(address->classId), true, + NULL, 1, skey); + + /* we expect exactly one match */ + tuple = systable_getnext(scan); + systable_endscan(scan); + table_close(rel, AccessShareLock); + + return (HeapTupleIsValid(tuple)); + } +} + /* * Return ObjectType for the given object type as given by * getObjectTypeDescription; if no valid ObjectType code exists, but it's a diff --git a/src/backend/catalog/pg_aggregate.c b/src/backend/catalog/pg_aggregate.c index 90fc7db949..a47e3c5507 100644 --- a/src/backend/catalog/pg_aggregate.c +++ b/src/backend/catalog/pg_aggregate.c @@ -748,12 +748,14 @@ AggregateCreate(const char *aggName, /* Depends on transition function */ ObjectAddressSet(referenced, ProcedureRelationId, transfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, transfn); /* Depends on final function, if any */ if (OidIsValid(finalfn)) { ObjectAddressSet(referenced, ProcedureRelationId, finalfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, finalfn); } /* Depends on combine function, if any */ @@ -761,6 +763,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, combinefn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, combinefn); } /* Depends on serialization function, if any */ @@ -768,6 +771,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, serialfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, serialfn); } /* Depends on deserialization function, if any */ @@ -775,6 +779,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, deserialfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, deserialfn); } /* Depends on forward transition function, if any */ @@ -782,6 +787,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, mtransfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, mtransfn); } /* Depends on inverse transition function, if any */ @@ -789,6 +795,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, minvtransfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, minvtransfn); } /* Depends on final function, if any */ @@ -796,6 +803,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, ProcedureRelationId, mfinalfn); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, mfinalfn); } /* Depends on sort operator, if any */ @@ -803,6 +811,7 @@ AggregateCreate(const char *aggName, { ObjectAddressSet(referenced, OperatorRelationId, sortop); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(OperatorRelationId, sortop); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); diff --git a/src/backend/catalog/pg_attrdef.c b/src/backend/catalog/pg_attrdef.c index 003ae70b4d..dcce454f00 100644 --- a/src/backend/catalog/pg_attrdef.c +++ b/src/backend/catalog/pg_attrdef.c @@ -178,6 +178,7 @@ StoreAttrDefault(Relation rel, AttrNumber attnum, colobject.objectId = RelationGetRelid(rel); colobject.objectSubId = attnum; + LockNotPinnedObject(RelationRelationId, RelationGetRelid(rel)); recordDependencyOn(&defobject, &colobject, attgenerated ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO); diff --git a/src/backend/catalog/pg_cast.c b/src/backend/catalog/pg_cast.c index 5a5b855d51..d3707e424c 100644 --- a/src/backend/catalog/pg_cast.c +++ b/src/backend/catalog/pg_cast.c @@ -97,16 +97,19 @@ CastCreate(Oid sourcetypeid, Oid targettypeid, /* dependency on source type */ ObjectAddressSet(referenced, TypeRelationId, sourcetypeid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, sourcetypeid); /* dependency on target type */ ObjectAddressSet(referenced, TypeRelationId, targettypeid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, targettypeid); /* dependency on function */ if (OidIsValid(funcid)) { ObjectAddressSet(referenced, ProcedureRelationId, funcid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, funcid); } /* dependencies on casts required for function */ @@ -114,11 +117,13 @@ CastCreate(Oid sourcetypeid, Oid targettypeid, { ObjectAddressSet(referenced, CastRelationId, incastid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(CastRelationId, incastid); } if (OidIsValid(outcastid)) { ObjectAddressSet(referenced, CastRelationId, outcastid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(CastRelationId, outcastid); } record_object_address_dependencies(&myself, addrs, behavior); diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c index 7f2f701229..78498b8c20 100644 --- a/src/backend/catalog/pg_collation.c +++ b/src/backend/catalog/pg_collation.c @@ -218,6 +218,7 @@ CollationCreate(const char *collname, Oid collnamespace, referenced.classId = NamespaceRelationId; referenced.objectId = collnamespace; referenced.objectSubId = 0; + LockNotPinnedObject(NamespaceRelationId, collnamespace); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* create dependency on owner */ diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c index 54f3fb50a5..8999c997f9 100644 --- a/src/backend/catalog/pg_constraint.c +++ b/src/backend/catalog/pg_constraint.c @@ -256,17 +256,26 @@ CreateConstraintEntry(const char *constraintName, if (constraintNTotalKeys > 0) { + bool locked_object = false; + for (i = 0; i < constraintNTotalKeys; i++) { ObjectAddressSubSet(relobject, RelationRelationId, relId, constraintKey[i]); add_exact_object_address(&relobject, addrs_auto); + + if (!locked_object) + { + LockNotPinnedObject(RelationRelationId, relId); + locked_object = true; + } } } else { ObjectAddressSet(relobject, RelationRelationId, relId); add_exact_object_address(&relobject, addrs_auto); + LockNotPinnedObject(RelationRelationId, relId); } } @@ -279,6 +288,7 @@ CreateConstraintEntry(const char *constraintName, ObjectAddressSet(domobject, TypeRelationId, domainId); add_exact_object_address(&domobject, addrs_auto); + LockNotPinnedObject(TypeRelationId, domainId); } record_object_address_dependencies(&conobject, addrs_auto, @@ -298,17 +308,26 @@ CreateConstraintEntry(const char *constraintName, if (foreignNKeys > 0) { + bool locked_object = false; + for (i = 0; i < foreignNKeys; i++) { ObjectAddressSubSet(relobject, RelationRelationId, foreignRelId, foreignKey[i]); add_exact_object_address(&relobject, addrs_normal); + + if (!locked_object) + { + LockNotPinnedObject(RelationRelationId, foreignRelId); + locked_object = true; + } } } else { ObjectAddressSet(relobject, RelationRelationId, foreignRelId); add_exact_object_address(&relobject, addrs_normal); + LockNotPinnedObject(RelationRelationId, foreignRelId); } } @@ -324,6 +343,7 @@ CreateConstraintEntry(const char *constraintName, ObjectAddressSet(relobject, RelationRelationId, indexRelId); add_exact_object_address(&relobject, addrs_normal); + LockNotPinnedObject(RelationRelationId, indexRelId); } if (foreignNKeys > 0) @@ -343,15 +363,18 @@ CreateConstraintEntry(const char *constraintName, { oprobject.objectId = pfEqOp[i]; add_exact_object_address(&oprobject, addrs_normal); + LockNotPinnedObject(OperatorRelationId, pfEqOp[i]); if (ppEqOp[i] != pfEqOp[i]) { oprobject.objectId = ppEqOp[i]; add_exact_object_address(&oprobject, addrs_normal); + LockNotPinnedObject(OperatorRelationId, ppEqOp[i]); } if (ffEqOp[i] != pfEqOp[i]) { oprobject.objectId = ffEqOp[i]; add_exact_object_address(&oprobject, addrs_normal); + LockNotPinnedObject(OperatorRelationId, ffEqOp[i]); } } } @@ -863,9 +886,12 @@ ConstraintSetParentConstraint(Oid childConstrId, ObjectAddressSet(depender, ConstraintRelationId, childConstrId); ObjectAddressSet(referenced, ConstraintRelationId, parentConstrId); + LockNotPinnedObject(ConstraintRelationId, parentConstrId); recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, childTableId); + + LockNotPinnedObject(RelationRelationId, childTableId); recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_SEC); } else diff --git a/src/backend/catalog/pg_conversion.c b/src/backend/catalog/pg_conversion.c index 0770878eac..25881654d6 100644 --- a/src/backend/catalog/pg_conversion.c +++ b/src/backend/catalog/pg_conversion.c @@ -116,12 +116,14 @@ ConversionCreate(const char *conname, Oid connamespace, referenced.classId = ProcedureRelationId; referenced.objectId = conproc; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, conproc); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* create dependency on namespace */ referenced.classId = NamespaceRelationId; referenced.objectId = connamespace; referenced.objectSubId = 0; + LockNotPinnedObject(NamespaceRelationId, connamespace); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* create dependency on owner */ diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c index 2b4514e8a3..d9760d7d05 100644 --- a/src/backend/catalog/pg_depend.c +++ b/src/backend/catalog/pg_depend.c @@ -20,19 +20,20 @@ #include "catalog/catalog.h" #include "catalog/dependency.h" #include "catalog/indexing.h" +#include "catalog/pg_auth_members.h" #include "catalog/pg_constraint.h" #include "catalog/pg_depend.h" #include "catalog/pg_extension.h" #include "catalog/partition.h" #include "commands/extension.h" #include "miscadmin.h" +#include "storage/lmgr.h" +#include "storage/lock.h" #include "utils/fmgroids.h" #include "utils/lsyscache.h" #include "utils/rel.h" -static bool isObjectPinned(const ObjectAddress *object); - /* * Record a dependency between 2 objects via their respective objectAddress. @@ -99,6 +100,37 @@ recordMultipleDependencies(const ObjectAddress *depender, slot_init_count = 0; for (i = 0; i < nreferenced; i++, referenced++) { +#ifdef USE_ASSERT_CHECKING + if (!isObjectPinned(referenced)) + { + if (referenced->classId != RelationRelationId) + { + LOCKTAG tag; + + SET_LOCKTAG_OBJECT(tag, + MyDatabaseId, + referenced->classId, + referenced->objectId, + 0); + /* assert the referenced object is locked */ + Assert(LockHeldByMe(&tag, AccessShareLock, false)); + } + else + { + Assert(!IsSharedRelation(referenced->objectId)); + + /* + * Assert the referenced object is locked if it should be + * visible (see the comment related to LockNotPinnedObject() + * in TypeCreate()). + */ + Assert(!ObjectByIdExist(referenced) || + CheckRelationOidLockedByMe(referenced->objectId, + AccessShareLock, true)); + } + } +#endif + /* * If the referenced object is pinned by the system, there's no real * need to record dependencies on it. This saves lots of space in @@ -238,6 +270,7 @@ recordDependencyOnCurrentExtension(const ObjectAddress *object, extension.objectId = CurrentExtensionObject; extension.objectSubId = 0; + LockNotPinnedObject(ExtensionRelationId, CurrentExtensionObject); recordDependencyOn(object, &extension, DEPENDENCY_EXTENSION); } } @@ -705,7 +738,7 @@ changeDependenciesOn(Oid refClassId, Oid oldRefObjectId, * The passed subId, if any, is ignored; we assume that only whole objects * are pinned (and that this implies pinning their components). */ -static bool +bool isObjectPinned(const ObjectAddress *object) { return IsPinnedObject(object->classId, object->objectId); diff --git a/src/backend/catalog/pg_operator.c b/src/backend/catalog/pg_operator.c index 65b45a424a..e8374eec88 100644 --- a/src/backend/catalog/pg_operator.c +++ b/src/backend/catalog/pg_operator.c @@ -251,6 +251,16 @@ OperatorShellMake(const char *operatorName, values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(InvalidOid); values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(InvalidOid); + /* Lock dependent objects */ + if (OidIsValid(operatorNamespace)) + LockNotPinnedObject(NamespaceRelationId, operatorNamespace); + + if (OidIsValid(leftTypeId)) + LockNotPinnedObject(TypeRelationId, leftTypeId); + + if (OidIsValid(rightTypeId)) + LockNotPinnedObject(TypeRelationId, rightTypeId); + /* * create a new operator tuple */ @@ -513,6 +523,15 @@ OperatorCreate(const char *operatorName, CatalogTupleInsert(pg_operator_desc, tup); } + /* Lock dependent objects */ + LockNotPinnedObject(NamespaceRelationId, operatorNamespace); + LockNotPinnedObject(TypeRelationId, leftTypeId); + LockNotPinnedObject(TypeRelationId, rightTypeId); + LockNotPinnedObject(TypeRelationId, operResultType); + LockNotPinnedObject(ProcedureRelationId, procedureId); + LockNotPinnedObject(ProcedureRelationId, restrictionId); + LockNotPinnedObject(ProcedureRelationId, joinId); + /* Add dependencies for the entry */ address = makeOperatorDependencies(tup, true, isUpdate); diff --git a/src/backend/catalog/pg_proc.c b/src/backend/catalog/pg_proc.c index 528c17cd7f..116e524390 100644 --- a/src/backend/catalog/pg_proc.c +++ b/src/backend/catalog/pg_proc.c @@ -593,6 +593,13 @@ ProcedureCreate(const char *procedureName, if (is_update) deleteDependencyRecordsFor(ProcedureRelationId, retval, true); + /* + * CommandCounterIncrement() here to ensure the new function entry is + * visible when LockNotPinnedObject() will check its existence before + * recording the dependencies. + */ + CommandCounterIncrement(); + addrs = new_object_addresses(); ObjectAddressSet(myself, ProcedureRelationId, retval); @@ -600,20 +607,24 @@ ProcedureCreate(const char *procedureName, /* dependency on namespace */ ObjectAddressSet(referenced, NamespaceRelationId, procNamespace); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(NamespaceRelationId, procNamespace); /* dependency on implementation language */ ObjectAddressSet(referenced, LanguageRelationId, languageObjectId); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(LanguageRelationId, languageObjectId); /* dependency on return type */ ObjectAddressSet(referenced, TypeRelationId, returnType); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, returnType); /* dependency on transform used by return type, if any */ if ((trfid = get_transform_oid(returnType, languageObjectId, true))) { ObjectAddressSet(referenced, TransformRelationId, trfid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TransformRelationId, trfid); } /* dependency on parameter types */ @@ -621,12 +632,14 @@ ProcedureCreate(const char *procedureName, { ObjectAddressSet(referenced, TypeRelationId, allParams[i]); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, allParams[i]); /* dependency on transform used by parameter type, if any */ if ((trfid = get_transform_oid(allParams[i], languageObjectId, true))) { ObjectAddressSet(referenced, TransformRelationId, trfid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TransformRelationId, trfid); } } @@ -635,6 +648,7 @@ ProcedureCreate(const char *procedureName, { ObjectAddressSet(referenced, ProcedureRelationId, prosupport); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, prosupport); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); @@ -674,9 +688,6 @@ ProcedureCreate(const char *procedureName, ArrayType *set_items = NULL; int save_nestlevel = 0; - /* Advance command counter so new tuple can be seen by validator */ - CommandCounterIncrement(); - /* * Set per-function configuration parameters so that the validation is * done with the environment the function expects. However, if diff --git a/src/backend/catalog/pg_publication.c b/src/backend/catalog/pg_publication.c index 7e5e357fd9..35e7425ac6 100644 --- a/src/backend/catalog/pg_publication.c +++ b/src/backend/catalog/pg_publication.c @@ -395,6 +395,7 @@ publication_add_relation(Oid pubid, PublicationRelInfo *pri, referenced; List *relids = NIL; int i; + bool locked = false; rel = table_open(PublicationRelRelationId, RowExclusiveLock); @@ -457,10 +458,13 @@ publication_add_relation(Oid pubid, PublicationRelInfo *pri, /* Add dependency on the publication */ ObjectAddressSet(referenced, PublicationRelationId, pubid); + LockNotPinnedObject(PublicationRelationId, pubid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* Add dependency on the relation */ ObjectAddressSet(referenced, RelationRelationId, relid); + + LockNotPinnedObject(RelationRelationId, relid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* Add dependency on the objects mentioned in the qualifications */ @@ -474,6 +478,11 @@ publication_add_relation(Oid pubid, PublicationRelInfo *pri, while ((i = bms_next_member(attnums, i)) >= 0) { ObjectAddressSubSet(referenced, RelationRelationId, relid, i); + if (!locked) + { + LockNotPinnedObject(RelationRelationId, relid); + locked = true; + } recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } @@ -643,10 +652,12 @@ publication_add_schema(Oid pubid, Oid schemaid, bool if_not_exists) /* Add dependency on the publication */ ObjectAddressSet(referenced, PublicationRelationId, pubid); + LockNotPinnedObject(PublicationRelationId, pubid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* Add dependency on the schema */ ObjectAddressSet(referenced, NamespaceRelationId, schemaid); + LockNotPinnedObject(NamespaceRelationId, schemaid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* Close the table */ diff --git a/src/backend/catalog/pg_range.c b/src/backend/catalog/pg_range.c index 501a6ba410..e5b5a0b6f8 100644 --- a/src/backend/catalog/pg_range.c +++ b/src/backend/catalog/pg_range.c @@ -70,26 +70,31 @@ RangeCreate(Oid rangeTypeOid, Oid rangeSubType, Oid rangeCollation, ObjectAddressSet(referenced, TypeRelationId, rangeSubType); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, rangeSubType); ObjectAddressSet(referenced, OperatorClassRelationId, rangeSubOpclass); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(OperatorClassRelationId, rangeSubOpclass); if (OidIsValid(rangeCollation)) { ObjectAddressSet(referenced, CollationRelationId, rangeCollation); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(CollationRelationId, rangeCollation); } if (OidIsValid(rangeCanonical)) { ObjectAddressSet(referenced, ProcedureRelationId, rangeCanonical); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, rangeCanonical); } if (OidIsValid(rangeSubDiff)) { ObjectAddressSet(referenced, ProcedureRelationId, rangeSubDiff); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, rangeSubDiff); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); @@ -99,6 +104,7 @@ RangeCreate(Oid rangeTypeOid, Oid rangeSubType, Oid rangeCollation, referencing.classId = TypeRelationId; referencing.objectId = multirangeTypeOid; referencing.objectSubId = 0; + LockNotPinnedObject(TypeRelationId, rangeTypeOid); recordDependencyOn(&referencing, &myself, DEPENDENCY_INTERNAL); table_close(pg_range, RowExclusiveLock); diff --git a/src/backend/catalog/pg_type.c b/src/backend/catalog/pg_type.c index 395dec8ed8..82ee7bc2e3 100644 --- a/src/backend/catalog/pg_type.c +++ b/src/backend/catalog/pg_type.c @@ -157,6 +157,12 @@ TypeShellMake(const char *typeName, Oid typeNamespace, Oid ownerId) * Create dependencies. We can/must skip this in bootstrap mode. */ if (!IsBootstrapProcessingMode()) + { + /* Lock dependent objects */ + LockNotPinnedObject(NamespaceRelationId, typeNamespace); + LockNotPinnedObject(ProcedureRelationId, F_SHELL_IN); + LockNotPinnedObject(ProcedureRelationId, F_SHELL_OUT); + GenerateTypeDependencies(tup, pg_type_desc, NULL, @@ -166,6 +172,7 @@ TypeShellMake(const char *typeName, Oid typeNamespace, Oid ownerId) false, true, /* make extension dependency */ false); + } /* Post creation hook for new shell type */ InvokeObjectPostCreateHook(TypeRelationId, typoid, 0); @@ -494,6 +501,37 @@ TypeCreate(Oid newTypeOid, * Create dependencies. We can/must skip this in bootstrap mode. */ if (!IsBootstrapProcessingMode()) + { + /* + * CommandCounterIncrement() here to ensure the new type entry is + * visible when LockNotPinnedObject() will check its existence before + * recording the dependencies. + */ + CommandCounterIncrement(); + + /* Lock dependent objects */ + LockNotPinnedObject(NamespaceRelationId, typeNamespace); + LockNotPinnedObject(ProcedureRelationId, inputProcedure); + LockNotPinnedObject(ProcedureRelationId, outputProcedure); + LockNotPinnedObject(ProcedureRelationId, receiveProcedure); + LockNotPinnedObject(ProcedureRelationId, sendProcedure); + LockNotPinnedObject(ProcedureRelationId, typmodinProcedure); + LockNotPinnedObject(ProcedureRelationId, typmodoutProcedure); + LockNotPinnedObject(ProcedureRelationId, analyzeProcedure); + LockNotPinnedObject(ProcedureRelationId, subscriptProcedure); + LockNotPinnedObject(TypeRelationId, baseType); + LockNotPinnedObject(CollationRelationId, typeCollation); + LockNotPinnedObject(TypeRelationId, elementType); + + /* + * No need to call LockRelationOid() (through LockNotPinnedObject()) + * on relationOid as relationOid is set to an InvalidOid or to a new + * Oid not added to pg_class yet (In heap_create_with_catalog(), + * AddNewRelationType() is called before AddNewRelationTuple()). + */ + if (relationKind == RELKIND_COMPOSITE_TYPE) + LockNotPinnedObject(TypeRelationId, typeObjectId); + GenerateTypeDependencies(tup, pg_type_desc, (defaultTypeBin ? @@ -505,6 +543,7 @@ TypeCreate(Oid newTypeOid, isDependentType, true, /* make extension dependency */ rebuildDeps); + } /* Post creation hook for new type */ InvokeObjectPostCreateHook(TypeRelationId, typeObjectId, 0); diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c index ad3082c62a..039c824dab 100644 --- a/src/backend/catalog/toasting.c +++ b/src/backend/catalog/toasting.c @@ -383,6 +383,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid, toastobject.objectId = toast_relid; toastobject.objectSubId = 0; + LockNotPinnedObject(RelationRelationId, relOid); recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL); } diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c index 4f99ebb447..57e86f576a 100644 --- a/src/backend/commands/alter.c +++ b/src/backend/commands/alter.c @@ -501,7 +501,10 @@ ExecAlterObjectDependsStmt(AlterObjectDependsStmt *stmt, ObjectAddress *refAddre currexts = getAutoExtensionsOfObject(address.classId, address.objectId); if (!list_member_oid(currexts, refAddr.objectId)) + { + LockNotPinnedObject(refAddr.classId, refAddr.objectId); recordDependencyOn(&address, &refAddr, DEPENDENCY_AUTO_EXTENSION); + } } return address; @@ -807,6 +810,7 @@ AlterObjectNamespace_internal(Relation rel, Oid objid, Oid nspOid) pfree(replaces); /* update dependency to point to the new schema */ + LockNotPinnedObject(NamespaceRelationId, nspOid); if (changeDependencyFor(classId, objid, NamespaceRelationId, oldNspOid, nspOid) != 1) elog(ERROR, "could not change schema dependency for object %u", diff --git a/src/backend/commands/amcmds.c b/src/backend/commands/amcmds.c index aaa0f9a1dc..8616a7c9fa 100644 --- a/src/backend/commands/amcmds.c +++ b/src/backend/commands/amcmds.c @@ -104,6 +104,7 @@ CreateAccessMethod(CreateAmStmt *stmt) referenced.objectId = amhandler; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, amhandler); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); recordDependencyOnCurrentExtension(&myself, false); diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c index ae0863d9a2..f30ba63ee1 100644 --- a/src/backend/commands/cluster.c +++ b/src/backend/commands/cluster.c @@ -1271,6 +1271,7 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, */ if (relam1 != relam2) { + LockNotPinnedObject(AccessMethodRelationId, relam2); if (changeDependencyFor(RelationRelationId, r1, AccessMethodRelationId, @@ -1279,6 +1280,8 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, elog(ERROR, "could not change access method dependency for relation \"%s.%s\"", get_namespace_name(get_rel_namespace(r1)), get_rel_name(r1)); + + LockNotPinnedObject(AccessMethodRelationId, relam1); if (changeDependencyFor(RelationRelationId, r2, AccessMethodRelationId, @@ -1380,6 +1383,8 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, { baseobject.objectId = r1; toastobject.objectId = relform1->reltoastrelid; + + LockNotPinnedObject(RelationRelationId, r1); recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL); } @@ -1388,6 +1393,8 @@ swap_relation_files(Oid r1, Oid r2, bool target_is_pg_class, { baseobject.objectId = r2; toastobject.objectId = relform2->reltoastrelid; + + LockNotPinnedObject(RelationRelationId, r2); recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL); } diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c index a586d246ec..5359aaf239 100644 --- a/src/backend/commands/event_trigger.c +++ b/src/backend/commands/event_trigger.c @@ -327,6 +327,7 @@ insert_event_trigger_tuple(const char *trigname, const char *eventname, Oid evtO referenced.classId = ProcedureRelationId; referenced.objectId = funcoid; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, funcoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* Depend on extension, if any. */ diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c index ec71761377..6656937126 100644 --- a/src/backend/commands/extension.c +++ b/src/backend/commands/extension.c @@ -2031,6 +2031,7 @@ InsertExtensionTuple(const char *extName, Oid extOwner, ObjectAddressSet(nsp, NamespaceRelationId, schemaOid); add_exact_object_address(&nsp, refobjs); + LockNotPinnedObject(NamespaceRelationId, schemaOid); foreach(lc, requiredExtensions) { @@ -2039,6 +2040,7 @@ InsertExtensionTuple(const char *extName, Oid extOwner, ObjectAddressSet(otherext, ExtensionRelationId, reqext); add_exact_object_address(&otherext, refobjs); + LockNotPinnedObject(ExtensionRelationId, reqext); } /* Record all of them (this includes duplicate elimination) */ @@ -3075,6 +3077,7 @@ AlterExtensionNamespace(const char *extensionName, const char *newschema, Oid *o table_close(extRel, RowExclusiveLock); /* update dependency to point to the new schema */ + LockNotPinnedObject(NamespaceRelationId, nspOid); if (changeDependencyFor(ExtensionRelationId, extensionOid, NamespaceRelationId, oldNspOid, nspOid) != 1) elog(ERROR, "could not change schema dependency for extension %s", @@ -3365,6 +3368,7 @@ ApplyExtensionUpdates(Oid extensionOid, otherext.objectId = reqext; otherext.objectSubId = 0; + LockNotPinnedObject(ExtensionRelationId, reqext); recordDependencyOn(&myself, &otherext, DEPENDENCY_NORMAL); } @@ -3521,6 +3525,7 @@ ExecAlterExtensionContentsRecurse(AlterExtensionContentsStmt *stmt, /* * OK, add the dependency. */ + LockNotPinnedObject(extension.classId, extension.objectId); recordDependencyOn(&object, &extension, DEPENDENCY_EXTENSION); /* diff --git a/src/backend/commands/foreigncmds.c b/src/backend/commands/foreigncmds.c index cf61bbac1f..735bca486c 100644 --- a/src/backend/commands/foreigncmds.c +++ b/src/backend/commands/foreigncmds.c @@ -642,6 +642,7 @@ CreateForeignDataWrapper(ParseState *pstate, CreateFdwStmt *stmt) referenced.classId = ProcedureRelationId; referenced.objectId = fdwhandler; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, fdwhandler); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } @@ -650,6 +651,7 @@ CreateForeignDataWrapper(ParseState *pstate, CreateFdwStmt *stmt) referenced.classId = ProcedureRelationId; referenced.objectId = fdwvalidator; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, fdwvalidator); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } @@ -811,6 +813,7 @@ AlterForeignDataWrapper(ParseState *pstate, AlterFdwStmt *stmt) referenced.classId = ProcedureRelationId; referenced.objectId = fdwhandler; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, fdwhandler); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } @@ -819,6 +822,7 @@ AlterForeignDataWrapper(ParseState *pstate, AlterFdwStmt *stmt) referenced.classId = ProcedureRelationId; referenced.objectId = fdwvalidator; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, fdwvalidator); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } } @@ -951,6 +955,7 @@ CreateForeignServer(CreateForeignServerStmt *stmt) referenced.classId = ForeignDataWrapperRelationId; referenced.objectId = fdw->fdwid; referenced.objectSubId = 0; + LockNotPinnedObject(ForeignDataWrapperRelationId, fdw->fdwid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); recordDependencyOnOwner(ForeignServerRelationId, srvId, ownerId); @@ -1195,6 +1200,7 @@ CreateUserMapping(CreateUserMappingStmt *stmt) referenced.classId = ForeignServerRelationId; referenced.objectId = srv->serverid; referenced.objectSubId = 0; + LockNotPinnedObject(ForeignServerRelationId, srv->serverid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); if (OidIsValid(useId)) @@ -1472,6 +1478,7 @@ CreateForeignTable(CreateForeignTableStmt *stmt, Oid relid) referenced.classId = ForeignServerRelationId; referenced.objectId = server->serverid; referenced.objectSubId = 0; + LockNotPinnedObject(ForeignServerRelationId, server->serverid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); table_close(ftrel, RowExclusiveLock); diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c index d43b89d3ef..4b0c203acb 100644 --- a/src/backend/commands/functioncmds.c +++ b/src/backend/commands/functioncmds.c @@ -1446,6 +1446,7 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt) /* Add or replace dependency on support function */ if (OidIsValid(procForm->prosupport)) { + LockNotPinnedObject(ProcedureRelationId, newsupport); if (changeDependencyFor(ProcedureRelationId, funcOid, ProcedureRelationId, procForm->prosupport, newsupport) != 1) @@ -1459,6 +1460,7 @@ AlterFunction(ParseState *pstate, AlterFunctionStmt *stmt) referenced.classId = ProcedureRelationId; referenced.objectId = newsupport; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, newsupport); recordDependencyOn(&address, &referenced, DEPENDENCY_NORMAL); } @@ -1975,21 +1977,25 @@ CreateTransform(CreateTransformStmt *stmt) /* dependency on language */ ObjectAddressSet(referenced, LanguageRelationId, langid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(LanguageRelationId, langid); /* dependency on type */ ObjectAddressSet(referenced, TypeRelationId, typeid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(TypeRelationId, typeid); /* dependencies on functions */ if (OidIsValid(fromsqlfuncid)) { ObjectAddressSet(referenced, ProcedureRelationId, fromsqlfuncid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, fromsqlfuncid); } if (OidIsValid(tosqlfuncid)) { ObjectAddressSet(referenced, ProcedureRelationId, tosqlfuncid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, tosqlfuncid); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c index 2f652463e3..2799742826 100644 --- a/src/backend/commands/indexcmds.c +++ b/src/backend/commands/indexcmds.c @@ -4517,8 +4517,10 @@ IndexSetParentIndex(Relation partitionIdx, Oid parentOid) ObjectAddressSet(parentIdx, RelationRelationId, parentOid); ObjectAddressSet(partitionTbl, RelationRelationId, partitionIdx->rd_index->indrelid); + LockNotPinnedObject(RelationRelationId, parentOid); recordDependencyOn(&partIdx, &parentIdx, DEPENDENCY_PARTITION_PRI); + LockNotPinnedObject(RelationRelationId, partitionIdx->rd_index->indrelid); recordDependencyOn(&partIdx, &partitionTbl, DEPENDENCY_PARTITION_SEC); } diff --git a/src/backend/commands/opclasscmds.c b/src/backend/commands/opclasscmds.c index b8b5c147c5..e70afd216c 100644 --- a/src/backend/commands/opclasscmds.c +++ b/src/backend/commands/opclasscmds.c @@ -298,12 +298,14 @@ CreateOpFamily(CreateOpFamilyStmt *stmt, const char *opfname, referenced.classId = AccessMethodRelationId; referenced.objectId = amoid; referenced.objectSubId = 0; + LockNotPinnedObject(AccessMethodRelationId, amoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* dependency on namespace */ referenced.classId = NamespaceRelationId; referenced.objectId = namespaceoid; referenced.objectSubId = 0; + LockNotPinnedObject(NamespaceRelationId, namespaceoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* dependency on owner */ @@ -725,18 +727,21 @@ DefineOpClass(CreateOpClassStmt *stmt) referenced.classId = NamespaceRelationId; referenced.objectId = namespaceoid; referenced.objectSubId = 0; + LockNotPinnedObject(NamespaceRelationId, namespaceoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* dependency on opfamily */ referenced.classId = OperatorFamilyRelationId; referenced.objectId = opfamilyoid; referenced.objectSubId = 0; + LockNotPinnedObject(OperatorFamilyRelationId, opfamilyoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); /* dependency on indexed datatype */ referenced.classId = TypeRelationId; referenced.objectId = typeoid; referenced.objectSubId = 0; + LockNotPinnedObject(TypeRelationId, typeoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); /* dependency on storage datatype */ @@ -745,6 +750,7 @@ DefineOpClass(CreateOpClassStmt *stmt) referenced.classId = TypeRelationId; referenced.objectId = storageoid; referenced.objectSubId = 0; + LockNotPinnedObject(TypeRelationId, storageoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } @@ -1486,6 +1492,13 @@ storeOperators(List *opfamilyname, Oid amoid, Oid opfamilyoid, heap_freetuple(tup); + /* + * CommandCounterIncrement() here to ensure the new operator entry is + * visible when LockNotPinnedObject() will check its existence before + * recording the dependencies. + */ + CommandCounterIncrement(); + /* Make its dependencies */ myself.classId = AccessMethodOperatorRelationId; myself.objectId = entryoid; @@ -1496,6 +1509,7 @@ storeOperators(List *opfamilyname, Oid amoid, Oid opfamilyoid, referenced.objectSubId = 0; /* see comments in amapi.h about dependency strength */ + LockNotPinnedObject(OperatorRelationId, op->object); recordDependencyOn(&myself, &referenced, op->ref_is_hard ? DEPENDENCY_NORMAL : DEPENDENCY_AUTO); @@ -1504,6 +1518,7 @@ storeOperators(List *opfamilyname, Oid amoid, Oid opfamilyoid, referenced.objectId = op->refobjid; referenced.objectSubId = 0; + LockNotPinnedObject(referenced.classId, op->refobjid); recordDependencyOn(&myself, &referenced, op->ref_is_hard ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO); @@ -1514,6 +1529,7 @@ storeOperators(List *opfamilyname, Oid amoid, Oid opfamilyoid, referenced.objectId = op->sortfamily; referenced.objectSubId = 0; + LockNotPinnedObject(OperatorFamilyRelationId, op->sortfamily); recordDependencyOn(&myself, &referenced, op->ref_is_hard ? DEPENDENCY_NORMAL : DEPENDENCY_AUTO); } @@ -1597,6 +1613,7 @@ storeProcedures(List *opfamilyname, Oid amoid, Oid opfamilyoid, referenced.objectSubId = 0; /* see comments in amapi.h about dependency strength */ + LockNotPinnedObject(ProcedureRelationId, proc->object); recordDependencyOn(&myself, &referenced, proc->ref_is_hard ? DEPENDENCY_NORMAL : DEPENDENCY_AUTO); @@ -1605,6 +1622,7 @@ storeProcedures(List *opfamilyname, Oid amoid, Oid opfamilyoid, referenced.objectId = proc->refobjid; referenced.objectSubId = 0; + LockNotPinnedObject(referenced.classId, proc->refobjid); recordDependencyOn(&myself, &referenced, proc->ref_is_hard ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO); diff --git a/src/backend/commands/operatorcmds.c b/src/backend/commands/operatorcmds.c index 5872a3e192..58a69e7cc2 100644 --- a/src/backend/commands/operatorcmds.c +++ b/src/backend/commands/operatorcmds.c @@ -33,6 +33,7 @@ #include "access/htup_details.h" #include "access/table.h" +#include "catalog/dependency.h" #include "catalog/indexing.h" #include "catalog/objectaccess.h" #include "catalog/pg_namespace.h" @@ -656,11 +657,15 @@ AlterOperator(AlterOperatorStmt *stmt) { replaces[Anum_pg_operator_oprrest - 1] = true; values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(restrictionOid); + if (OidIsValid(restrictionOid)) + LockNotPinnedObject(ProcedureRelationId, restrictionOid); } if (updateJoin) { replaces[Anum_pg_operator_oprjoin - 1] = true; values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(joinOid); + if (OidIsValid(joinOid)) + LockNotPinnedObject(ProcedureRelationId, joinOid); } if (OidIsValid(commutatorOid)) { @@ -688,6 +693,31 @@ AlterOperator(AlterOperatorStmt *stmt) CatalogTupleUpdate(catalog, &tup->t_self, tup); + + /* Lock dependent objects */ + oprForm = (Form_pg_operator) GETSTRUCT(tup); + + if (OidIsValid(oprForm->oprnamespace)) + LockNotPinnedObject(NamespaceRelationId, oprForm->oprnamespace); + + if (OidIsValid(oprForm->oprleft)) + LockNotPinnedObject(TypeRelationId, oprForm->oprleft); + + if (OidIsValid(oprForm->oprright)) + LockNotPinnedObject(TypeRelationId, oprForm->oprright); + + if (OidIsValid(oprForm->oprresult)) + LockNotPinnedObject(TypeRelationId, oprForm->oprresult); + + if (OidIsValid(oprForm->oprcode)) + LockNotPinnedObject(ProcedureRelationId, oprForm->oprcode); + + if (OidIsValid(oprForm->oprrest)) + LockNotPinnedObject(ProcedureRelationId, oprForm->oprrest); + + if (OidIsValid(oprForm->oprjoin)) + LockNotPinnedObject(ProcedureRelationId, oprForm->oprjoin); + address = makeOperatorDependencies(tup, false, true); if (OidIsValid(commutatorOid) || OidIsValid(negatorOid)) diff --git a/src/backend/commands/policy.c b/src/backend/commands/policy.c index 6ff3eba824..9da98cbeec 100644 --- a/src/backend/commands/policy.c +++ b/src/backend/commands/policy.c @@ -722,6 +722,7 @@ CreatePolicy(CreatePolicyStmt *stmt) myself.objectId = policy_id; myself.objectSubId = 0; + LockNotPinnedObject(RelationRelationId, table_id); recordDependencyOn(&myself, &target, DEPENDENCY_AUTO); recordDependencyOnExpr(&myself, qual, qual_pstate->p_rtable, @@ -1053,6 +1054,7 @@ AlterPolicy(AlterPolicyStmt *stmt) myself.objectId = policy_id; myself.objectSubId = 0; + LockNotPinnedObject(RelationRelationId, table_id); recordDependencyOn(&myself, &target, DEPENDENCY_AUTO); recordDependencyOnExpr(&myself, qual, qual_parse_rtable, DEPENDENCY_NORMAL); diff --git a/src/backend/commands/proclang.c b/src/backend/commands/proclang.c index 881f90017e..fadfd9064f 100644 --- a/src/backend/commands/proclang.c +++ b/src/backend/commands/proclang.c @@ -190,12 +190,14 @@ CreateProceduralLanguage(CreatePLangStmt *stmt) /* dependency on the PL handler function */ ObjectAddressSet(referenced, ProcedureRelationId, handlerOid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, handlerOid); /* dependency on the inline handler function, if any */ if (OidIsValid(inlineOid)) { ObjectAddressSet(referenced, ProcedureRelationId, inlineOid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, inlineOid); } /* dependency on the validator function, if any */ @@ -203,6 +205,7 @@ CreateProceduralLanguage(CreatePLangStmt *stmt) { ObjectAddressSet(referenced, ProcedureRelationId, valOid); add_exact_object_address(&referenced, addrs); + LockNotPinnedObject(ProcedureRelationId, valOid); } record_object_address_dependencies(&myself, addrs, DEPENDENCY_NORMAL); diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c index 0188e8bbd5..d7ba2e59e6 100644 --- a/src/backend/commands/sequence.c +++ b/src/backend/commands/sequence.c @@ -1691,6 +1691,8 @@ process_owned_by(Relation seqrel, List *owned_by, bool for_identity) depobject.classId = RelationRelationId; depobject.objectId = RelationGetRelid(seqrel); depobject.objectSubId = 0; + + LockNotPinnedObject(RelationRelationId, RelationGetRelid(tablerel)); recordDependencyOn(&depobject, &refobject, deptype); } diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c index 1db3ef69d2..9f0b03388a 100644 --- a/src/backend/commands/statscmds.c +++ b/src/backend/commands/statscmds.c @@ -88,6 +88,7 @@ CreateStatistics(CreateStatsStmt *stmt) bool build_mcv; bool build_expressions; bool requested_type = false; + bool locked_object = false; int i; ListCell *cell; ListCell *cell2; @@ -536,6 +537,12 @@ CreateStatistics(CreateStatsStmt *stmt) for (i = 0; i < nattnums; i++) { ObjectAddressSubSet(parentobject, RelationRelationId, relid, attnums[i]); + + if (!locked_object) + { + LockNotPinnedObject(RelationRelationId, relid); + locked_object = true; + } recordDependencyOn(&myself, &parentobject, DEPENDENCY_AUTO); } @@ -553,6 +560,8 @@ CreateStatistics(CreateStatsStmt *stmt) if (!nattnums) { ObjectAddressSet(parentobject, RelationRelationId, relid); + + LockNotPinnedObject(RelationRelationId, relid); recordDependencyOn(&myself, &parentobject, DEPENDENCY_AUTO); } @@ -573,6 +582,7 @@ CreateStatistics(CreateStatsStmt *stmt) * than the underlying table(s). */ ObjectAddressSet(parentobject, NamespaceRelationId, namespaceId); + LockNotPinnedObject(NamespaceRelationId, namespaceId); recordDependencyOn(&myself, &parentobject, DEPENDENCY_NORMAL); recordDependencyOnOwner(StatisticExtRelationId, statoid, stxowner); diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index e14bc0c054..ea775bf531 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -3445,6 +3445,7 @@ StoreCatalogInheritance1(Oid relationId, Oid parentOid, childobject.objectId = relationId; childobject.objectSubId = 0; + LockNotPinnedObject(RelationRelationId, parentOid); recordDependencyOn(&childobject, &parentobject, child_dependency_type(child_is_partition)); @@ -7367,7 +7368,9 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel, /* * Add needed dependency entries for the new column. */ + LockNotPinnedObject(TypeRelationId, attribute->atttypid); add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid); + LockNotPinnedObject(CollationRelationId, attribute->attcollation); add_column_collation_dependency(myrelid, newattnum, attribute->attcollation); /* @@ -10311,11 +10314,16 @@ addFkConstraint(addFkConstraintSides fkside, Assert(fkside != addFkBothSides); if (fkside == addFkReferencedSide) + { + LockNotPinnedObject(ConstraintRelationId, parentConstr); recordDependencyOn(&address, &referenced, DEPENDENCY_INTERNAL); + } else { + LockNotPinnedObject(ConstraintRelationId, parentConstr); recordDependencyOn(&address, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(rel)); + LockNotPinnedObject(RelationRelationId, RelationGetRelid(rel)); recordDependencyOn(&address, &referenced, DEPENDENCY_PARTITION_SEC); } } @@ -13495,7 +13503,9 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel, table_close(attrelation, RowExclusiveLock); /* Install dependencies on new datatype and collation */ + LockNotPinnedObject(TypeRelationId, targettype); add_column_datatype_dependency(RelationGetRelid(rel), attnum, targettype); + LockNotPinnedObject(CollationRelationId, targetcollid); add_column_collation_dependency(RelationGetRelid(rel), attnum, targetcollid); /* @@ -15058,6 +15068,7 @@ ATExecSetAccessMethodNoStorage(Relation rel, Oid newAccessMethodId) */ ObjectAddressSet(relobj, RelationRelationId, reloid); ObjectAddressSet(referenced, AccessMethodRelationId, rd_rel->relam); + LockNotPinnedObject(AccessMethodRelationId, rd_rel->relam); recordDependencyOn(&relobj, &referenced, DEPENDENCY_NORMAL); } else if (OidIsValid(oldAccessMethodId) && @@ -15077,6 +15088,7 @@ ATExecSetAccessMethodNoStorage(Relation rel, Oid newAccessMethodId) OidIsValid(rd_rel->relam)); /* Both are valid, so update the dependency */ + LockNotPinnedObject(AccessMethodRelationId, rd_rel->relam); changeDependencyFor(RelationRelationId, reloid, AccessMethodRelationId, oldAccessMethodId, rd_rel->relam); @@ -16679,6 +16691,7 @@ ATExecAddOf(Relation rel, const TypeName *ofTypename, LOCKMODE lockmode) typeobj.classId = TypeRelationId; typeobj.objectId = typeid; typeobj.objectSubId = 0; + LockNotPinnedObject(TypeRelationId, typeid); recordDependencyOn(&tableobj, &typeobj, DEPENDENCY_NORMAL); /* Update pg_class.reloftype */ @@ -17445,14 +17458,17 @@ AlterRelationNamespaceInternal(Relation classRel, Oid relOid, /* Update dependency on schema if caller said so */ - if (hasDependEntry && - changeDependencyFor(RelationRelationId, + if (hasDependEntry) + { + LockNotPinnedObject(NamespaceRelationId, newNspOid); + if (changeDependencyFor(RelationRelationId, relOid, NamespaceRelationId, oldNspOid, newNspOid) != 1) - elog(ERROR, "could not change schema dependency for relation \"%s\"", - NameStr(classForm->relname)); + elog(ERROR, "could not change schema dependency for relation \"%s\"", + NameStr(classForm->relname)); + } } else UnlockTuple(classRel, &classTup->t_self, InplaceUpdateTupleLock); diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c index 09356e46d1..f1782f0c65 100644 --- a/src/backend/commands/trigger.c +++ b/src/backend/commands/trigger.c @@ -1019,8 +1019,6 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, ((Form_pg_class) GETSTRUCT(tuple))->relhastriggers = true; CatalogTupleUpdate(pgrel, &tuple->t_self, tuple); - - CommandCounterIncrement(); } else CacheInvalidateRelcacheByTuple(tuple); @@ -1028,6 +1026,13 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, heap_freetuple(tuple); table_close(pgrel, RowExclusiveLock); + /* + * CommandCounterIncrement() here to ensure the new trigger entry is + * visible when LockNotPinnedObject() will check its existence before + * recording the dependencies. + */ + CommandCounterIncrement(); + /* * If we're replacing a trigger, flush all the old dependencies before * recording new ones. @@ -1046,6 +1051,7 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, referenced.classId = ProcedureRelationId; referenced.objectId = funcoid; referenced.objectSubId = 0; + LockNotPinnedObject(ProcedureRelationId, funcoid); recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); if (isInternal && OidIsValid(constraintOid)) @@ -1059,6 +1065,7 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, referenced.classId = ConstraintRelationId; referenced.objectId = constraintOid; referenced.objectSubId = 0; + LockNotPinnedObject(ConstraintRelationId, constraintOid); recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL); } else @@ -1071,6 +1078,8 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, referenced.classId = RelationRelationId; referenced.objectId = RelationGetRelid(rel); referenced.objectSubId = 0; + + LockNotPinnedObject(RelationRelationId, RelationGetRelid(rel)); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); if (OidIsValid(constrrelid)) @@ -1078,6 +1087,8 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, referenced.classId = RelationRelationId; referenced.objectId = constrrelid; referenced.objectSubId = 0; + + LockNotPinnedObject(RelationRelationId, constrrelid); recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO); } /* Not possible to have an index dependency in this case */ @@ -1092,6 +1103,7 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, referenced.classId = ConstraintRelationId; referenced.objectId = constraintOid; referenced.objectSubId = 0; + LockNotPinnedObject(TriggerRelationId, trigoid); recordDependencyOn(&referenced, &myself, DEPENDENCY_INTERNAL); } @@ -1101,8 +1113,11 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, if (OidIsValid(parentTriggerOid)) { ObjectAddressSet(referenced, TriggerRelationId, parentTriggerOid); + LockNotPinnedObject(TriggerRelationId, parentTriggerOid); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(rel)); + + LockNotPinnedObject(RelationRelationId, RelationGetRelid(rel)); recordDependencyOn(&myself, &referenced, DEPENDENCY_PARTITION_SEC); } } @@ -1111,12 +1126,19 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString, if (columns != NULL) { int i; + bool locked_object = false; referenced.classId = RelationRelationId; referenced.objectId = RelationGetRelid(rel); for (i = 0; i < ncolumns; i++) { referenced.objectSubId = columns[i]; + + if (!locked_object) + { + LockNotPinnedObject(RelationRelationId, RelationGetRelid(rel)); + locked_object = true; + } recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL); } } @@ -1256,9 +1278,12 @@ TriggerSetParentTrigger(Relation trigRel, ObjectAddressSet(depender, TriggerRelationId, childTrigId); ObjectAddressSet(referenced, TriggerRelationId, parentTrigId); + LockNotPinnedObject(TriggerRelationId, parentTrigId); recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_PRI); ObjectAddressSet(referenced, RelationRelationId, childTableId); + + LockNotPinnedObject(RelationRelationId, childTableId); recordDependencyOn(&depender, &referenced, DEPENDENCY_PARTITION_SEC); } else diff --git a/src/backend/commands/tsearchcmds.c b/src/backend/commands/tsearchcmds.c index b7b5019f1e..1b90e187ea 100644 --- a/src/backend/commands/tsearchcmds.c +++ b/src/backend/commands/tsearchcmds.c @@ -214,6 +214,7 @@ DefineTSParser(List *names, List *parameters) namestrcpy(&pname, prsname); values[Anum_pg_ts_parser_prsname - 1] = NameGetDatum(&pname); values[Anum_pg_ts_parser_prsnamespace - 1] = ObjectIdGetDatum(namespaceoid); + LockNotPinnedObject(NamespaceRelationId, namespaceoid); /* * loop over the definition list and extract the information we need. @@ -224,28 +225,48 @@ DefineTSParser(List *names, List *parameters) if (strcmp(defel->defname, "start") == 0) { + Oid procoid; + values[Anum_pg_ts_parser_prsstart - 1] = get_ts_parser_func(defel, Anum_pg_ts_parser_prsstart); + procoid = DatumGetObjectId(values[Anum_pg_ts_parser_prsstart - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else if (strcmp(defel->defname, "gettoken") == 0) { + Oid procoid; + values[Anum_pg_ts_parser_prstoken - 1] = get_ts_parser_func(defel, Anum_pg_ts_parser_prstoken); + procoid = DatumGetObjectId(values[Anum_pg_ts_parser_prstoken - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else if (strcmp(defel->defname, "end") == 0) { + Oid procoid; + values[Anum_pg_ts_parser_prsend - 1] = get_ts_parser_func(defel, Anum_pg_ts_parser_prsend); + procoid = DatumGetObjectId(values[Anum_pg_ts_parser_prsend - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else if (strcmp(defel->defname, "headline") == 0) { + Oid procoid; + values[Anum_pg_ts_parser_prsheadline - 1] = get_ts_parser_func(defel, Anum_pg_ts_parser_prsheadline); + procoid = DatumGetObjectId(values[Anum_pg_ts_parser_prsheadline - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else if (strcmp(defel->defname, "lextypes") == 0) { + Oid procoid; + values[Anum_pg_ts_parser_prslextype - 1] = get_ts_parser_func(defel, Anum_pg_ts_parser_prslextype); + procoid = DatumGetObjectId(values[Anum_pg_ts_parser_prslextype - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else ereport(ERROR, @@ -474,6 +495,10 @@ DefineTSDictionary(List *names, List *parameters) CatalogTupleInsert(dictRel, tup); + /* Lock dependent objects */ + LockNotPinnedObject(NamespaceRelationId, namespaceoid); + LockNotPinnedObject(TSTemplateRelationId, templId); + address = makeDictionaryDependencies(tup); /* Post creation hook for new text search dictionary */ @@ -723,6 +748,7 @@ DefineTSTemplate(List *names, List *parameters) namestrcpy(&dname, tmplname); values[Anum_pg_ts_template_tmplname - 1] = NameGetDatum(&dname); values[Anum_pg_ts_template_tmplnamespace - 1] = ObjectIdGetDatum(namespaceoid); + LockNotPinnedObject(NamespaceRelationId, namespaceoid); /* * loop over the definition list and extract the information we need. @@ -733,15 +759,23 @@ DefineTSTemplate(List *names, List *parameters) if (strcmp(defel->defname, "init") == 0) { + Oid procoid; + values[Anum_pg_ts_template_tmplinit - 1] = get_ts_template_func(defel, Anum_pg_ts_template_tmplinit); nulls[Anum_pg_ts_template_tmplinit - 1] = false; + procoid = DatumGetObjectId(values[Anum_pg_ts_template_tmplinit - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else if (strcmp(defel->defname, "lexize") == 0) { + Oid procoid; + values[Anum_pg_ts_template_tmpllexize - 1] = get_ts_template_func(defel, Anum_pg_ts_template_tmpllexize); nulls[Anum_pg_ts_template_tmpllexize - 1] = false; + procoid = DatumGetObjectId(values[Anum_pg_ts_template_tmpllexize - 1]); + LockNotPinnedObject(ProcedureRelationId, procoid); } else ereport(ERROR, @@ -998,6 +1032,10 @@ DefineTSConfiguration(List *names, List *parameters, ObjectAddress *copied) values[Anum_pg_ts_config_cfgowner - 1] = ObjectIdGetDatum(GetUserId()); values[Anum_pg_ts_config_cfgparser - 1] = ObjectIdGetDatum(prsOid); + /* Lock dependent objects */ + LockNotPinnedObject(NamespaceRelationId, namespaceoid); + LockNotPinnedObject(TSParserRelationId, prsOid); + tup = heap_form_tuple(cfgRel->rd_att, values, nulls); CatalogTupleInsert(cfgRel, tup); @@ -1063,6 +1101,7 @@ DefineTSConfiguration(List *names, List *parameters, ObjectAddress *copied) slot[slot_stored_count]->tts_values[Anum_pg_ts_config_map_mapseqno - 1] = cfgmap->mapseqno; slot[slot_stored_count]->tts_values[Anum_pg_ts_config_map_mapdict - 1] = cfgmap->mapdict; + LockNotPinnedObject(TSDictionaryRelationId, cfgmap->mapdict); ExecStoreVirtualTuple(slot[slot_stored_count]); slot_stored_count++; @@ -1156,9 +1195,13 @@ ObjectAddress AlterTSConfiguration(AlterTSConfigurationStmt *stmt) { HeapTuple tup; + Form_pg_ts_config cfg; Oid cfgId; Relation relMap; ObjectAddress address; + ScanKeyData skey; + SysScanDesc scan; + HeapTuple maptup; /* Find the configuration */ tup = GetTSConfigTuple(stmt->cfgname); @@ -1168,7 +1211,8 @@ AlterTSConfiguration(AlterTSConfigurationStmt *stmt) errmsg("text search configuration \"%s\" does not exist", NameListToString(stmt->cfgname)))); - cfgId = ((Form_pg_ts_config) GETSTRUCT(tup))->oid; + cfg = (Form_pg_ts_config) GETSTRUCT(tup); + cfgId = cfg->oid; /* must be owner */ if (!object_ownercheck(TSConfigRelationId, cfgId, GetUserId())) @@ -1183,6 +1227,28 @@ AlterTSConfiguration(AlterTSConfigurationStmt *stmt) else if (stmt->tokentype) DropConfigurationMapping(stmt, tup, relMap); + /* Lock dependent objects */ + + ScanKeyInit(&skey, + Anum_pg_ts_config_map_mapcfg, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(cfgId)); + + scan = systable_beginscan(relMap, TSConfigMapIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid((maptup = systable_getnext(scan)))) + { + Form_pg_ts_config_map cfgmap = (Form_pg_ts_config_map) GETSTRUCT(maptup); + + LockNotPinnedObject(TSDictionaryRelationId, cfgmap->mapdict); + } + + systable_endscan(scan); + + LockNotPinnedObject(NamespaceRelationId, cfg->cfgnamespace); + LockNotPinnedObject(TSParserRelationId, cfg->cfgparser); + /* Update dependencies */ makeConfigurationDependencies(tup, true, relMap); @@ -1414,6 +1480,8 @@ MakeConfigurationMapping(AlterTSConfigurationStmt *stmt, repl_val[Anum_pg_ts_config_map_mapdict - 1] = ObjectIdGetDatum(dictNew); repl_repl[Anum_pg_ts_config_map_mapdict - 1] = true; + LockNotPinnedObject(TSDictionaryRelationId, dictNew); + newtup = heap_modify_tuple(maptup, RelationGetDescr(relMap), repl_val, repl_null, repl_repl); @@ -1456,6 +1524,9 @@ MakeConfigurationMapping(AlterTSConfigurationStmt *stmt, slot[slotCount]->tts_values[Anum_pg_ts_config_map_mapseqno - 1] = Int32GetDatum(j + 1); slot[slotCount]->tts_values[Anum_pg_ts_config_map_mapdict - 1] = ObjectIdGetDatum(dictIds[j]); + /* Lock dependent objects */ + LockNotPinnedObject(TSDictionaryRelationId, dictIds[j]); + ExecStoreVirtualTuple(slot[slotCount]); slotCount++; diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c index 2a6550de90..25be046308 100644 --- a/src/backend/commands/typecmds.c +++ b/src/backend/commands/typecmds.c @@ -1794,6 +1794,7 @@ makeRangeConstructors(const char *name, Oid namespace, * that they go away silently when the type is dropped. Note that * pg_dump depends on this choice to avoid dumping the constructors. */ + LockNotPinnedObject(TypeRelationId, rangeOid); recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL); } } @@ -1859,6 +1860,7 @@ makeMultirangeConstructors(const char *name, Oid namespace, * that they go away silently when the type is dropped. Note that pg_dump * depends on this choice to avoid dumping the constructors. */ + LockNotPinnedObject(TypeRelationId, multirangeOid); recordDependencyOn(&myself, &referenced, DEPENDENCY_INTERNAL); pfree(argtypes); @@ -2672,6 +2674,45 @@ AlterDomainDefault(List *names, Node *defaultRaw) CatalogTupleUpdate(rel, &tup->t_self, newtuple); + /* Lock dependent objects */ + typTup = (Form_pg_type) GETSTRUCT(newtuple); + + if (OidIsValid(typTup->typnamespace)) + LockNotPinnedObject(NamespaceRelationId, typTup->typnamespace); + + if (OidIsValid(typTup->typinput)) + LockNotPinnedObject(ProcedureRelationId, typTup->typinput); + + if (OidIsValid(typTup->typoutput)) + LockNotPinnedObject(ProcedureRelationId, typTup->typoutput); + + if (OidIsValid(typTup->typreceive)) + LockNotPinnedObject(ProcedureRelationId, typTup->typreceive); + + if (OidIsValid(typTup->typsend)) + LockNotPinnedObject(ProcedureRelationId, typTup->typsend); + + if (OidIsValid(typTup->typmodin)) + LockNotPinnedObject(ProcedureRelationId, typTup->typmodin); + + if (OidIsValid(typTup->typmodout)) + LockNotPinnedObject(ProcedureRelationId, typTup->typmodout); + + if (OidIsValid(typTup->typanalyze)) + LockNotPinnedObject(ProcedureRelationId, typTup->typanalyze); + + if (OidIsValid(typTup->typsubscript)) + LockNotPinnedObject(ProcedureRelationId, typTup->typsubscript); + + if (OidIsValid(typTup->typbasetype)) + LockNotPinnedObject(TypeRelationId, typTup->typbasetype); + + if (OidIsValid(typTup->typcollation)) + LockNotPinnedObject(CollationRelationId, typTup->typcollation); + + if (OidIsValid(typTup->typelem)) + LockNotPinnedObject(TypeRelationId, typTup->typelem); + /* Rebuild dependencies */ GenerateTypeDependencies(newtuple, rel, @@ -4278,10 +4319,13 @@ AlterTypeNamespaceInternal(Oid typeOid, Oid nspOid, if (oldNspOid != nspOid && (isCompositeType || typform->typtype != TYPTYPE_COMPOSITE) && !isImplicitArray) + { + LockNotPinnedObject(NamespaceRelationId, nspOid); if (changeDependencyFor(TypeRelationId, typeOid, NamespaceRelationId, oldNspOid, nspOid) != 1) elog(ERROR, "could not change schema dependency for type \"%s\"", format_type_be(typeOid)); + } InvokeObjectPostAlterHook(TypeRelationId, typeOid, 0); @@ -4573,6 +4617,7 @@ AlterTypeRecurse(Oid typeOid, bool isImplicitArray, SysScanDesc scan; ScanKeyData key[1]; HeapTuple domainTup; + Form_pg_type typeForm; /* Since this function recurses, it could be driven to stack overflow */ check_stack_depth(); @@ -4621,6 +4666,45 @@ AlterTypeRecurse(Oid typeOid, bool isImplicitArray, newtup = heap_modify_tuple(tup, RelationGetDescr(catalog), values, nulls, replaces); + /* Lock dependent objects */ + typeForm = (Form_pg_type) GETSTRUCT(newtup); + + if (OidIsValid(typeForm->typnamespace)) + LockNotPinnedObject(NamespaceRelationId, typeForm->typnamespace); + + if (OidIsValid(typeForm->typinput)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typinput); + + if (OidIsValid(typeForm->typoutput)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typoutput); + + if (OidIsValid(typeForm->typreceive)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typreceive); + + if (OidIsValid(typeForm->typsend)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typsend); + + if (OidIsValid(typeForm->typmodin)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typmodin); + + if (OidIsValid(typeForm->typmodout)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typmodout); + + if (OidIsValid(typeForm->typanalyze)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typanalyze); + + if (OidIsValid(typeForm->typsubscript)) + LockNotPinnedObject(ProcedureRelationId, typeForm->typsubscript); + + if (OidIsValid(typeForm->typbasetype)) + LockNotPinnedObject(TypeRelationId, typeForm->typbasetype); + + if (OidIsValid(typeForm->typcollation)) + LockNotPinnedObject(CollationRelationId, typeForm->typcollation); + + if (OidIsValid(typeForm->typelem)) + LockNotPinnedObject(TypeRelationId, typeForm->typelem); + CatalogTupleUpdate(catalog, &newtup->t_self, newtup); /* Rebuild dependencies for this type */ diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c index 6cc9a8d8bf..c930eca262 100644 --- a/src/backend/rewrite/rewriteDefine.c +++ b/src/backend/rewrite/rewriteDefine.c @@ -155,6 +155,7 @@ InsertRule(const char *rulname, referenced.objectId = eventrel_oid; referenced.objectSubId = 0; + LockNotPinnedObject(RelationRelationId, eventrel_oid); recordDependencyOn(&myself, &referenced, (evtype == CMD_SELECT) ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO); diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt index 97d91eb1e9..33b0c750e4 100644 --- a/src/backend/utils/errcodes.txt +++ b/src/backend/utils/errcodes.txt @@ -277,6 +277,7 @@ Section: Class 28 - Invalid Authorization Specification Section: Class 2B - Dependent Privilege Descriptors Still Exist 2B000 E ERRCODE_DEPENDENT_PRIVILEGE_DESCRIPTORS_STILL_EXIST dependent_privilege_descriptors_still_exist +2BP02 E ERRCODE_DEPENDENT_OBJECTS_DOES_NOT_EXIST dependent_objects_does_not_exist 2BP01 E ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST dependent_objects_still_exist Section: Class 2D - Invalid Transaction Termination diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h index 6908ca7180..0546bcbe16 100644 --- a/src/include/catalog/dependency.h +++ b/src/include/catalog/dependency.h @@ -101,6 +101,8 @@ typedef struct ObjectAddresses ObjectAddresses; /* in dependency.c */ extern void AcquireDeletionLock(const ObjectAddress *object, int flags); +extern void LockNotPinnedObjectById(const ObjectAddress *object); +extern void LockNotPinnedObject(Oid classid, Oid objid); extern void ReleaseDeletionLock(const ObjectAddress *object); @@ -172,6 +174,7 @@ extern long changeDependenciesOf(Oid classId, Oid oldObjectId, extern long changeDependenciesOn(Oid refClassId, Oid oldRefObjectId, Oid newRefObjectId); +extern bool isObjectPinned(const ObjectAddress *object); extern Oid getExtensionOfObject(Oid classId, Oid objectId); extern List *getAutoExtensionsOfObject(Oid classId, Oid objectId); diff --git a/src/include/catalog/objectaddress.h b/src/include/catalog/objectaddress.h index 3a70d80e32..56f746264b 100644 --- a/src/include/catalog/objectaddress.h +++ b/src/include/catalog/objectaddress.h @@ -53,6 +53,7 @@ extern void check_object_ownership(Oid roleid, Node *object, Relation relation); extern Oid get_object_namespace(const ObjectAddress *address); +extern bool ObjectByIdExist(const ObjectAddress *address); extern bool is_objectclass_supported(Oid class_id); extern const char *get_object_class_descr(Oid class_id); diff --git a/src/test/isolation/expected/test_dependencies_locks.out b/src/test/isolation/expected/test_dependencies_locks.out new file mode 100644 index 0000000000..9b645d7aa5 --- /dev/null +++ b/src/test/isolation/expected/test_dependencies_locks.out @@ -0,0 +1,129 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_begin s1_create_function_in_schema s2_drop_schema s1_commit +step s1_begin: BEGIN; +step s1_create_function_in_schema: CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; +step s2_drop_schema: DROP SCHEMA testschema; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_schema: <... completed> +ERROR: cannot drop schema testschema because other objects depend on it + +starting permutation: s2_begin s2_drop_schema s1_create_function_in_schema s2_commit +step s2_begin: BEGIN; +step s2_drop_schema: DROP SCHEMA testschema; +step s1_create_function_in_schema: CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_in_schema: <... completed> +ERROR: schema testschema does not exist + +starting permutation: s1_begin s1_alter_function_schema s2_drop_alterschema s1_commit +step s1_begin: BEGIN; +step s1_alter_function_schema: ALTER FUNCTION public.falter() SET SCHEMA alterschema; +step s2_drop_alterschema: DROP SCHEMA alterschema; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_alterschema: <... completed> +ERROR: cannot drop schema alterschema because other objects depend on it + +starting permutation: s2_begin s2_drop_alterschema s1_alter_function_schema s2_commit +step s2_begin: BEGIN; +step s2_drop_alterschema: DROP SCHEMA alterschema; +step s1_alter_function_schema: ALTER FUNCTION public.falter() SET SCHEMA alterschema; <waiting ...> +step s2_commit: COMMIT; +step s1_alter_function_schema: <... completed> +ERROR: schema alterschema does not exist + +starting permutation: s1_begin s1_create_function_with_argtype s2_drop_foo_type s1_commit +step s1_begin: BEGIN; +step s1_create_function_with_argtype: CREATE FUNCTION fooargtype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; +step s2_drop_foo_type: DROP TYPE public.foo; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_foo_type: <... completed> +ERROR: cannot drop type foo because other objects depend on it + +starting permutation: s2_begin s2_drop_foo_type s1_create_function_with_argtype s2_commit +step s2_begin: BEGIN; +step s2_drop_foo_type: DROP TYPE public.foo; +step s1_create_function_with_argtype: CREATE FUNCTION fooargtype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_with_argtype: <... completed> +ERROR: type foo does not exist + +starting permutation: s1_begin s1_create_function_with_rettype s2_drop_foo_rettype s1_commit +step s1_begin: BEGIN; +step s1_create_function_with_rettype: CREATE FUNCTION footrettype() RETURNS id LANGUAGE sql RETURN 1; +step s2_drop_foo_rettype: DROP DOMAIN id; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_foo_rettype: <... completed> +ERROR: cannot drop type id because other objects depend on it + +starting permutation: s2_begin s2_drop_foo_rettype s1_create_function_with_rettype s2_commit +step s2_begin: BEGIN; +step s2_drop_foo_rettype: DROP DOMAIN id; +step s1_create_function_with_rettype: CREATE FUNCTION footrettype() RETURNS id LANGUAGE sql RETURN 1; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_with_rettype: <... completed> +ERROR: type id does not exist + +starting permutation: s1_begin s1_create_function_with_function s2_drop_function_f s1_commit +step s1_begin: BEGIN; +step s1_create_function_with_function: CREATE FUNCTION foofunc() RETURNS int LANGUAGE SQL RETURN f() + 1; +step s2_drop_function_f: DROP FUNCTION f(); <waiting ...> +step s1_commit: COMMIT; +step s2_drop_function_f: <... completed> +ERROR: cannot drop function f() because other objects depend on it + +starting permutation: s2_begin s2_drop_function_f s1_create_function_with_function s2_commit +step s2_begin: BEGIN; +step s2_drop_function_f: DROP FUNCTION f(); +step s1_create_function_with_function: CREATE FUNCTION foofunc() RETURNS int LANGUAGE SQL RETURN f() + 1; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_with_function: <... completed> +ERROR: function f() does not exist + +starting permutation: s1_begin s1_create_domain_with_domain s2_drop_domain_id s1_commit +step s1_begin: BEGIN; +step s1_create_domain_with_domain: CREATE DOMAIN idid as id; +step s2_drop_domain_id: DROP DOMAIN id; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_domain_id: <... completed> +ERROR: cannot drop type id because other objects depend on it + +starting permutation: s2_begin s2_drop_domain_id s1_create_domain_with_domain s2_commit +step s2_begin: BEGIN; +step s2_drop_domain_id: DROP DOMAIN id; +step s1_create_domain_with_domain: CREATE DOMAIN idid as id; <waiting ...> +step s2_commit: COMMIT; +step s1_create_domain_with_domain: <... completed> +ERROR: type id does not exist + +starting permutation: s1_begin s1_create_table_with_type s2_drop_footab_type s1_commit +step s1_begin: BEGIN; +step s1_create_table_with_type: CREATE TABLE tabtype(a footab); +step s2_drop_footab_type: DROP TYPE public.footab; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_footab_type: <... completed> +ERROR: cannot drop type footab because other objects depend on it + +starting permutation: s2_begin s2_drop_footab_type s1_create_table_with_type s2_commit +step s2_begin: BEGIN; +step s2_drop_footab_type: DROP TYPE public.footab; +step s1_create_table_with_type: CREATE TABLE tabtype(a footab); <waiting ...> +step s2_commit: COMMIT; +step s1_create_table_with_type: <... completed> +ERROR: type footab does not exist + +starting permutation: s1_begin s1_create_server_with_fdw_wrapper s2_drop_fdw_wrapper s1_commit +step s1_begin: BEGIN; +step s1_create_server_with_fdw_wrapper: CREATE SERVER srv_fdw_wrapper FOREIGN DATA WRAPPER fdw_wrapper; +step s2_drop_fdw_wrapper: DROP FOREIGN DATA WRAPPER fdw_wrapper RESTRICT; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_fdw_wrapper: <... completed> +ERROR: cannot drop foreign-data wrapper fdw_wrapper because other objects depend on it + +starting permutation: s2_begin s2_drop_fdw_wrapper s1_create_server_with_fdw_wrapper s2_commit +step s2_begin: BEGIN; +step s2_drop_fdw_wrapper: DROP FOREIGN DATA WRAPPER fdw_wrapper RESTRICT; +step s1_create_server_with_fdw_wrapper: CREATE SERVER srv_fdw_wrapper FOREIGN DATA WRAPPER fdw_wrapper; <waiting ...> +step s2_commit: COMMIT; +step s1_create_server_with_fdw_wrapper: <... completed> +ERROR: foreign-data wrapper fdw_wrapper does not exist diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 143109aa4d..0e80dfecfb 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -115,3 +115,4 @@ test: serializable-parallel-2 test: serializable-parallel-3 test: matview-write-skew test: lock-nowait +test: test_dependencies_locks diff --git a/src/test/isolation/specs/test_dependencies_locks.spec b/src/test/isolation/specs/test_dependencies_locks.spec new file mode 100644 index 0000000000..5d04dfe9dc --- /dev/null +++ b/src/test/isolation/specs/test_dependencies_locks.spec @@ -0,0 +1,89 @@ +setup +{ + CREATE SCHEMA testschema; + CREATE SCHEMA alterschema; + CREATE TYPE public.foo as enum ('one', 'two'); + CREATE TYPE public.footab as enum ('three', 'four'); + CREATE DOMAIN id AS int; + CREATE FUNCTION f() RETURNS int LANGUAGE SQL RETURN 1; + CREATE FUNCTION public.falter() RETURNS int LANGUAGE SQL RETURN 1; + CREATE FOREIGN DATA WRAPPER fdw_wrapper; +} + +teardown +{ + DROP FUNCTION IF EXISTS testschema.foo(); + DROP FUNCTION IF EXISTS fooargtype(num foo); + DROP FUNCTION IF EXISTS footrettype(); + DROP FUNCTION IF EXISTS foofunc(); + DROP FUNCTION IF EXISTS public.falter(); + DROP FUNCTION IF EXISTS alterschema.falter(); + DROP DOMAIN IF EXISTS idid; + DROP SERVER IF EXISTS srv_fdw_wrapper; + DROP TABLE IF EXISTS tabtype; + DROP SCHEMA IF EXISTS testschema; + DROP SCHEMA IF EXISTS alterschema; + DROP TYPE IF EXISTS public.foo; + DROP TYPE IF EXISTS public.footab; + DROP DOMAIN IF EXISTS id; + DROP FUNCTION IF EXISTS f(); + DROP FOREIGN DATA WRAPPER IF EXISTS fdw_wrapper; +} + +session "s1" + +step "s1_begin" { BEGIN; } +step "s1_create_function_in_schema" { CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; } +step "s1_create_function_with_argtype" { CREATE FUNCTION fooargtype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; } +step "s1_create_function_with_rettype" { CREATE FUNCTION footrettype() RETURNS id LANGUAGE sql RETURN 1; } +step "s1_create_function_with_function" { CREATE FUNCTION foofunc() RETURNS int LANGUAGE SQL RETURN f() + 1; } +step "s1_alter_function_schema" { ALTER FUNCTION public.falter() SET SCHEMA alterschema; } +step "s1_create_domain_with_domain" { CREATE DOMAIN idid as id; } +step "s1_create_table_with_type" { CREATE TABLE tabtype(a footab); } +step "s1_create_server_with_fdw_wrapper" { CREATE SERVER srv_fdw_wrapper FOREIGN DATA WRAPPER fdw_wrapper; } +step "s1_commit" { COMMIT; } + +session "s2" + +step "s2_begin" { BEGIN; } +step "s2_drop_schema" { DROP SCHEMA testschema; } +step "s2_drop_alterschema" { DROP SCHEMA alterschema; } +step "s2_drop_foo_type" { DROP TYPE public.foo; } +step "s2_drop_foo_rettype" { DROP DOMAIN id; } +step "s2_drop_footab_type" { DROP TYPE public.footab; } +step "s2_drop_function_f" { DROP FUNCTION f(); } +step "s2_drop_domain_id" { DROP DOMAIN id; } +step "s2_drop_fdw_wrapper" { DROP FOREIGN DATA WRAPPER fdw_wrapper RESTRICT; } +step "s2_commit" { COMMIT; } + +# function - schema +permutation "s1_begin" "s1_create_function_in_schema" "s2_drop_schema" "s1_commit" +permutation "s2_begin" "s2_drop_schema" "s1_create_function_in_schema" "s2_commit" + +# alter function - schema +permutation "s1_begin" "s1_alter_function_schema" "s2_drop_alterschema" "s1_commit" +permutation "s2_begin" "s2_drop_alterschema" "s1_alter_function_schema" "s2_commit" + +# function - argtype +permutation "s1_begin" "s1_create_function_with_argtype" "s2_drop_foo_type" "s1_commit" +permutation "s2_begin" "s2_drop_foo_type" "s1_create_function_with_argtype" "s2_commit" + +# function - rettype +permutation "s1_begin" "s1_create_function_with_rettype" "s2_drop_foo_rettype" "s1_commit" +permutation "s2_begin" "s2_drop_foo_rettype" "s1_create_function_with_rettype" "s2_commit" + +# function - function +permutation "s1_begin" "s1_create_function_with_function" "s2_drop_function_f" "s1_commit" +permutation "s2_begin" "s2_drop_function_f" "s1_create_function_with_function" "s2_commit" + +# domain - domain +permutation "s1_begin" "s1_create_domain_with_domain" "s2_drop_domain_id" "s1_commit" +permutation "s2_begin" "s2_drop_domain_id" "s1_create_domain_with_domain" "s2_commit" + +# table - type +permutation "s1_begin" "s1_create_table_with_type" "s2_drop_footab_type" "s1_commit" +permutation "s2_begin" "s2_drop_footab_type" "s1_create_table_with_type" "s2_commit" + +# server - foreign data wrapper +permutation "s1_begin" "s1_create_server_with_fdw_wrapper" "s2_drop_fdw_wrapper" "s1_commit" +permutation "s2_begin" "s2_drop_fdw_wrapper" "s1_create_server_with_fdw_wrapper" "s2_commit" diff --git a/src/test/modules/test_oat_hooks/expected/alter_table.out b/src/test/modules/test_oat_hooks/expected/alter_table.out index 8cbacca2c9..df8d276dfc 100644 --- a/src/test/modules/test_oat_hooks/expected/alter_table.out +++ b/src/test/modules/test_oat_hooks/expected/alter_table.out @@ -37,6 +37,8 @@ NOTICE: in object access: superuser attempting create (subId=0x0) [internal] NOTICE: in object access: superuser finished create (subId=0x0) [internal] NOTICE: in object access: superuser attempting create (subId=0x0) [internal] NOTICE: in object access: superuser finished create (subId=0x0) [internal] +NOTICE: in object access: superuser attempting namespace search (subId=0x0) [no report on violation, allowed] +NOTICE: in object access: superuser finished namespace search (subId=0x0) [no report on violation, allowed] NOTICE: in process utility: superuser finished CREATE TABLE CREATE RULE test_oat_notify AS ON UPDATE TO test_oat_schema.test_oat_tab @@ -62,8 +64,6 @@ BEGIN END IF; END; $$; NOTICE: in process utility: superuser attempting CREATE FUNCTION -NOTICE: in object access: superuser attempting namespace search (subId=0x0) [no report on violation, allowed] -NOTICE: in object access: superuser finished namespace search (subId=0x0) [no report on violation, allowed] NOTICE: in object access: superuser attempting create (subId=0x0) [explicit] NOTICE: in object access: superuser finished create (subId=0x0) [explicit] NOTICE: in process utility: superuser finished CREATE FUNCTION diff --git a/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out b/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out index effdc49145..da6d931994 100644 --- a/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out +++ b/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out @@ -86,6 +86,8 @@ NOTICE: in object access: superuser attempting create (subId=0x0) [internal] NOTICE: in object access: superuser finished create (subId=0x0) [internal] NOTICE: in object access: superuser attempting create (subId=0x0) [internal] NOTICE: in object access: superuser finished create (subId=0x0) [internal] +NOTICE: in object access: superuser attempting namespace search (subId=0x0) [no report on violation, allowed] +NOTICE: in object access: superuser finished namespace search (subId=0x0) [no report on violation, allowed] NOTICE: in process utility: superuser finished CREATE TABLE CREATE INDEX regress_test_table_t_idx ON regress_test_table (t); NOTICE: in process utility: superuser attempting CREATE INDEX diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 143ae7c09c..a34e238024 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -2866,11 +2866,12 @@ begin; alter table alterlock2 add constraint alterlock2nv foreign key (f1) references alterlock (f1) NOT VALID; select * from my_locks order by 1; - relname | max_lockmode -------------+----------------------- - alterlock | ShareRowExclusiveLock - alterlock2 | ShareRowExclusiveLock -(2 rows) + relname | max_lockmode +----------------+----------------------- + alterlock | ShareRowExclusiveLock + alterlock2 | ShareRowExclusiveLock + alterlock_pkey | AccessShareLock +(3 rows) commit; begin; -- 2.34.1 --+nHX6Y4wAeAx6W3F-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <jian.universality@gmail.com> 0 siblings, 0 replies; 283+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 283+ messages in thread
end of thread, other threads:[~2025-10-20 05:29 UTC | newest] Thread overview: 283+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-04-04 00:24 [PATCH v3 3/3] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. Justin Pryzby <pryzbyj@telsasoft.com> 2021-04-04 00:24 [PATCH v2 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. Justin Pryzby <pryzbyj@telsasoft.com> 2021-04-04 00:24 [PATCH 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. Justin Pryzby <pryzbyj@telsasoft.com> 2024-03-29 15:43 [PATCH v17] Avoid orphaned objects dependencies Bertrand Drouvot <bertranddrouvot.pg@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH 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jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 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2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <jian.universality@gmail.com>
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